MODULE WindowManager;	(** AUTHOR "TF"; PURPOSE "Window manager implementation"; *)

IMPORT
	KernelLog, Kernel, Strings, Plugins, Inputs, Modules, Displays, Graphics := WMGraphics,
	Messages := WMMessages, DW := WMDefaultWindows,
	WM := WMWindowManager, Rect := WMRectangles, Raster,  WMFontManager (*Load*), Commands, Options;

CONST
	DirtyBufSize = 128;
	CombineLookahead = 64;
	XYResizeHandleSize = 15;
	ZF = 0.90; ZD = 0.1;

TYPE
	Window = WM.Window;
	Rectangle = Rect.Rectangle;

	ViewPort* = OBJECT (WM.ViewPort);
	VAR
		backbuffer : Graphics.Image;
		deviceRect : Rect.Rectangle;
		canvas : Graphics.BufferCanvas;
		state : Graphics.CanvasState;
		display : Displays.Display;
		internnavig, navig : BOOLEAN;
		lastx, lasty : LONGINT;
		lastKeys : SET;
		modifierKeys : SET;
		meta : BOOLEAN;
		fx, fy, inffx, inffy, factor, intfactor : REAL;

		PROCEDURE &New*(disp : Displays.Display);
		BEGIN
			display := disp;
			NEW(backbuffer);
			KernelLog.String("WindowManager: Display resolution: ");
			KernelLog.Int(disp.width, 0); KernelLog.Char("x"); KernelLog.Int(disp.height, 0);
			KernelLog.Char("x"); KernelLog.Int(disp.format * 8, 0); KernelLog.Ln;
			Raster.Create(backbuffer, disp.width, disp.height, Raster.DisplayFormat(disp.format));
			range.r := range.l + disp.width; range.b := range.t + disp.height;
			deviceRect.r := disp.width; deviceRect.b := disp.height;
			width0 := disp.width; height0 := disp.height;
			desc := "Graphics adapter view";
			NEW(canvas, backbuffer);
			canvas.SetFont(Graphics.GetDefaultFont());
			canvas.SaveState(state);
			factor := 1; intfactor := 1;
			fx := factor; fy := factor; inffx := 1 ; inffy := inffx;
			internnavig := FALSE;
			modifierKeys := {};
		END New;

		(**  Return the modifier keys that are pressed in the view *)
		PROCEDURE GetKeyState*(VAR state : SET);
		BEGIN
			state := modifierKeys
		END GetKeyState;

		PROCEDURE KeyEvent(ucs : LONGINT; flags : SET; keysym : LONGINT);
		VAR msg : Messages.Message; done : BOOLEAN; r : Rectangle; originX, originY : LONGINT; w, h : REAL;
		BEGIN
			manager.lock.AcquireWrite;
			modifierKeys := flags;
			msg.originator := SELF;
			IF (flags * Inputs.Ctrl # {}) & (flags * Inputs.Alt # {}) & (keysym = Inputs.KsDelete) THEN
				manager.lock.ReleaseWrite; Modules.Shutdown(Modules.Reboot); LOOP END
			END;
			meta := (flags * Inputs.Meta # {}) OR ((flags * Inputs.Alt # {}) & (flags * Inputs.Shift # {}));
			msg.msgType := Messages.MsgKey;
			msg.x := ucs;
			msg.y := keysym;
			msg.flags := flags;
			done := FALSE;
			IF meta THEN
				IF keysym = 0FF50H THEN (* Home key *)
					manager.GetPopulatedArea(r);
					SetRange(r.l, r.t, r.r - r.l, r.b - r.t, TRUE);
					done := TRUE
				ELSIF keysym = 0FF57H THEN (* End key *)
					originX := ENTIER((range.l + range.r - display.width) / 2);
					originY := ENTIER((range.t + range.b - display.height) / 2);
					SetRange(originX, originY, display.width, display.height, TRUE);
					done := TRUE
				ELSIF keysym = 0FF53H THEN (* right *)
					w :=  range.r - range.l; SetRange(range.l + w, range.t,  w, range.b - range.t, TRUE); done := TRUE
				ELSIF keysym = 0FF51H THEN (* left *)
					w :=  range.r - range.l; SetRange(range.l - w, range.t,  w, range.b - range.t, TRUE); done := TRUE
				ELSIF keysym = 0FF54H THEN (* bottom *)
					h :=  range.b - range.t; SetRange(range.l, range.t + h,  range.r - range.l, h, TRUE); done := TRUE
				ELSIF keysym = 0FF52H THEN (* top *)
					h :=  range.b - range.t; SetRange(range.l, range.t - h,  range.r - range.l, h, TRUE); done := TRUE
				ELSIF keysym = 0FF55H THEN (* pgup *)
					w :=  range.r - range.l; h :=  range.b - range.t; SetRange(range.l + w /4, range.t + h / 4,  w / 2, h / 2, TRUE); done := TRUE
				ELSIF keysym = 0FF56H THEN (* pgdn *)
					w :=  range.r - range.l; h :=  range.b - range.t; SetRange(range.l - w /2, range.t - h / 2,  w * 2, h * 2, TRUE); done := TRUE
				END
			END;
			IF ~done THEN manager.Handle(msg) END;
			manager.lock.ReleaseWrite
		END KeyEvent;

		PROCEDURE PointerEvent(x, y, z, dx, dy, dz : LONGINT; keys : SET);
		VAR
			msg : Messages.Message; of : REAL; i : LONGINT; ignore : BOOLEAN;
			centerX, centerY : REAL; w : Window;
		BEGIN
			ignore := FALSE;
			msg.originator := SELF;
			msg.msgType := Messages.MsgPointer;

			IF meta THEN
				manager.lock.AcquireWrite;
				w := manager(WindowManager).GetPositionOwnerIntern(ENTIER(range.l + x * inffx), ENTIER(range.t + y * inffy), SELF);
				IF (w # NIL) & (w # manager(WindowManager).bottom) THEN
					IF ((0 IN lastKeys) # (0 IN keys)) & (0 IN keys) THEN
						ZoomToWindow(w); ignore := TRUE
					ELSIF ((2 IN lastKeys) # (2 IN keys)) & (2 IN keys) THEN
						SetInitialWindowBounds(w);  ignore := TRUE
					END;					
				END;
				IF (dz # 0) THEN
					navig := TRUE;
					of := factor;
					IF (dz < 0) THEN
						FOR i := 0 TO ABS(dz) - 1 DO intfactor := (intfactor * ZF);
							IF intfactor < 0.001 * 0.001 THEN intfactor := 0.001 * 0.001 END
						END
					ELSE
						FOR i := 0 TO ABS(dz) - 1 DO intfactor := (intfactor * 1 / ZF);
							IF intfactor > 50 THEN factor := 50 END
						END
					END;
					IF ABS(intfactor - 1) < ZD THEN factor := 1
					ELSIF ABS(intfactor - 0.5) < ZD THEN factor := 0.5
					ELSIF ABS(intfactor - ENTIER(intfactor)) < 1/10 * (intfactor) THEN factor := ENTIER(intfactor)
					ELSE factor := intfactor
					END;

					IF of # factor THEN
						centerX := range.l + x * inffx; (*fof*) (** fof: lastx -> x *)
						centerY := range.t + y * inffy; (** fof: lasty -> y *)
						fx := factor; fy := factor; inffx := 1 / factor; inffy := inffx;
						centerX := centerX - ((x - 0.5 * backbuffer.width) * inffx);
						centerY := centerY - ((y - 0.5 * backbuffer.height) * inffy);

						range.l := centerX - inffx * 0.5 * backbuffer.width;
						range.t := centerY - inffy * 0.5 * backbuffer.height;
						range.r := centerX + inffx * 0.5 * backbuffer.width;
						range.b := centerY + inffy * 0.5 * backbuffer.height;
						manager.RefreshView(SELF)
					END;
					lastx := x; lasty := y; ignore := TRUE
				ELSIF ((x = 0) OR (y = 0) OR (x = backbuffer.width - 1) OR (y = backbuffer.height - 1))
					(* & ((ABS(dx) >1) OR (ABS(dy) > 1)) *) THEN
					IF (x = 0) OR (x = backbuffer.width - 1) THEN range.l := range.l + (inffx * dx); range.r := range.r  + (inffx * dx) END;
					IF (y = 0) OR (y = backbuffer.height - 1) THEN range.t := range.t + (inffy * dy); range.b := range.b  + (inffy * dy) END;
					lastx := x; lasty := y;
					navig := TRUE; manager.RefreshView(SELF)
				END;

				manager.lock.ReleaseWrite
			ELSE
				IF ~internnavig THEN IF navig THEN navig := FALSE; manager.RefreshView(SELF) END END;
				lastx := x; lasty := y
			END;

			lastKeys := keys;
			msg.x := ENTIER(range.l + x * inffx); msg.y := ENTIER(range.t + y * inffy); msg.z := z;
			msg.dx := ENTIER(dx * inffx); msg.dy := ENTIER(dy * inffy); msg.dz := dz;
			msg.flags := keys;
			IF ~ignore THEN
				IF manager # NIL THEN manager.Handle(msg) END;
			END;
		END PointerEvent;

		PROCEDURE ZoomToWindow(w : Window);
		VAR cur : WM.DecorList; r : Rectangle;
		BEGIN
			ASSERT(manager.lock.HasWriteLock());
			r := w.bounds;
			IF w.master # NIL THEN
				w := w.master;
				r := w.bounds;
				cur := w.decor;
				(* consider decoration *)
				WHILE cur # NIL DO Rect.ExtendRect(r, cur.w.bounds); cur := cur.next END;
			END;
			IF (r.r - r.l <  backbuffer.width) & (r.b - r.t < backbuffer.height) THEN
				SetRange(r.l, r.t, backbuffer.width, backbuffer.height, TRUE)
			ELSE
				SetRange(r.l, r.t, r.r - r.l, r.b - r.t, TRUE)
			END
		END ZoomToWindow;

		PROCEDURE SetInitialWindowBounds(w : Window);
		VAR width, height : LONGINT;
		BEGIN
			ASSERT(manager.lock.HasWriteLock());
			IF w.master # NIL THEN w := w.master END;
			width := w.initialBounds.r - w.initialBounds.l;
			height := w.initialBounds.b - w.initialBounds.t;
			(* set original bounds of the window *)
			manager.SetWindowSize(w, width, height);
		END SetInitialWindowBounds;

		(** Set the observed range. *)
		PROCEDURE SetRange*(x, y, w, h : REAL; showTransition : BOOLEAN);
		VAR
			sx, sy, sx2, sy2, dx, dy, dx2, dy2, x2, y2  : REAL;
			i, steps : LONGINT;
		CONST Steps = 16;

			PROCEDURE Set(x, y, w, h : REAL);
			VAR tf : REAL;
			BEGIN
				range.l := x;
				range.t := y;
				factor := (display.width) / w;
				tf := (display.height) / h;
				IF factor > tf THEN factor := tf END;
				fx := factor; fy := factor; inffx := 1 / factor; inffy := inffx;
				range.r := x + display.width * inffx;
				range.b := y + display.height * inffy;
				intfactor := factor;
				manager.RefreshView(SELF);
			END Set;

		BEGIN
			IF w = 0 THEN w := 0.001 END;
			IF h = 0 THEN h := 0.001 END;
			IF showTransition THEN
				sx := range.l; sy := range.t;
				sx2 := range.r; sy2 := range.b;
				x2 := x + w; y2 := y + h;
				steps := Steps;
				IF (sx = x) & (sy = y) & (sx2 - sx = w) & (sy2- sy = h) THEN steps := 1 END;
				dx := (x - sx) / steps;
				dy := (y - sy) / steps;
				dx2 := (x2 - sx2) / steps;
				dy2 := (y2 - sy2) / steps;

				internnavig := TRUE; navig := TRUE;
				FOR i := 1 TO steps-1 DO
					Set(sx + dx * i, sy + dy * i, (sx2 + dx2 * i) - (sx + dx * i), (sy2 + dy2 * i) - (sy + dy * i))
				END;
				internnavig := FALSE; navig := FALSE
			END;
			Set(x, y, w, h)
		END SetRange;

		(** r in wm coordinates *)
		PROCEDURE Update*(r : Rectangle; top : Window);
		BEGIN
			ASSERT(manager.lock.HasWriteLock());
			Draw(r (*fof: was Rect.ResizeRect(r, 1)*), top.prev) (* assuming the src -domain is only 1 *) (*?fof: what does this mean? For me this makes no sense *)
		END Update;

		PROCEDURE Refresh*(top : Window);
		BEGIN
			ASSERT(manager.lock.HasWriteLock());
			Update(Rect.MakeRect(ENTIER(range.l)-1, ENTIER(range.t)-1, ENTIER(range.r) + 1, ENTIER(range.b) + 1), top)
		END Refresh;

		PROCEDURE GetWMCoordinates*(CONST r : Rect.Rectangle) : Rect.Rectangle;
		VAR rect : Rect.Rectangle;
		BEGIN
			rect.l := ENTIER(range.l + r.l * inffx);
			rect.r := ENTIER(range.l + r.r * inffx + 0.5);
			rect.t := ENTIER(range.t + r.t * inffy);
			rect.b := ENTIER(range.t + r.b * inffy + 0.5);
			RETURN rect;
		END GetWMCoordinates;

		(* in wm coordinates *)
		PROCEDURE Draw(r : Rectangle; top : Window);
		VAR cur : Window;
			wr, nr : Rectangle;

			PROCEDURE InternalDraw(r : Rectangle; cur : Window);
			VAR nr, cb, tnr, dsr : Rectangle; width, height : LONGINT;
			BEGIN
				ASSERT(cur.isVisible);
				IF cur.useAlpha & (cur.prev # NIL)  THEN Draw(r, cur.prev)
				ELSE
					WHILE cur # NIL DO (* draw r in wm coordinates in all the windows from cur to top *)
						IF cur.isVisible & (~(WM.FlagNavigation IN cur.flags) OR (cur.view = SELF)) THEN
							IF (WM.FlagNavigation IN cur.flags) THEN
								cb := GetWMCoordinates(cur.bounds);
							ELSE
								cb := cur.bounds;
							END;
							nr := r; Rect.ClipRect(nr, cb);
							IF (WM.FlagNavigation IN cur.flags) THEN
								dsr.l := ENTIER((nr.l - range.l) * fx - fx); dsr.t := ENTIER((nr.t - range.t) * fy - fy);
								dsr.r := ENTIER((nr.r - range.l) * fx + fx + 0.5); dsr.b := ENTIER((nr.b - range.t) * fy + fy + 0.5);
							ELSE
								dsr.l := ENTIER((nr.l - range.l) * fx) ; dsr.t := ENTIER((nr.t - range.t) * fy);
								dsr.r := ENTIER((nr.r - range.l) * fx + 0.5); dsr.b := ENTIER((nr.b - range.t) * fy + 0.5);
							END;
							IF  (~Rect.RectEmpty(dsr)) & (Rect.Intersect(dsr, deviceRect)) THEN
								canvas.SetClipRect(dsr);  (* Set clip rect to dsr, clipped at current window *)
								(* range can not be factored out because of rounding *)
								IF  (WM.FlagNavigation IN cur.flags) THEN
									canvas.ClipRectAsNewLimits(cur.bounds.l, cur.bounds.t); (*ENTIER((cb.l - range.l) * fx), ENTIER((cb.t - range.t) * fy)); *)
									width := cur.GetWidth();
									height := cur.GetHeight();
								ELSE
									canvas.ClipRectAsNewLimits(ENTIER((cur.bounds.l - range.l) * fx), ENTIER((cur.bounds.t - range.t) * fy));
									width := ENTIER((cb.r - range.l)* fx) - ENTIER((cb.l - range.l) * fx);
									height := ENTIER((cb.b - range.t) * fy) - ENTIER((cb.t - range.t) * fy);
								END;


								IF navig THEN
									cur.Draw(canvas, width, height, Graphics.ScaleBox);
								ELSE
									cur.Draw(canvas, width, height, Graphics.ScaleBilinear);
								END;
								canvas.RestoreState(state);
							END;
						END;
						cur := cur.next
					END;
					tnr.l := ENTIER((r.l - range.l) * fx); tnr.t := ENTIER((r.t - range.t) * fy);
					tnr.r := ENTIER((r.r - range.l) * fx + 0.5); tnr.b := ENTIER((r.b - range.t) * fy + 0.5);
					ClipAtImage(tnr, backbuffer);
					IF ((tnr.l < tnr.r) & (tnr.t < tnr.b))  THEN
						display.Transfer(backbuffer.mem^, (tnr.l * backbuffer.fmt.bpp DIV 8) + tnr.t * backbuffer.bpr,
						backbuffer.bpr, tnr.l, tnr.t, tnr.r - tnr.l, tnr.b -  tnr.t, Displays.set)
					END
				END
			END InternalDraw;

		BEGIN
			ASSERT(manager.lock.HasWriteLock());
			cur := top;
			IF (cur # NIL) & (~Rect.RectEmpty(r)) THEN
				IF cur.isVisible & ~((WM.FlagNavigation IN cur.flags) & (cur.view # SELF)) THEN
					IF (WM.FlagNavigation IN cur.flags) THEN
						wr := GetWMCoordinates(cur.bounds);
					ELSE
						wr := cur.bounds;
					END;
					IF ~Rect.IsContained(wr, r) THEN
						IF Rect.Intersect(r, wr) THEN
							(* r contains wr calculate r -  wr and recursively call for resulting rectangles*)
							(* calculate top rectangle *)
							IF wr.t > r.t THEN Rect.SetRect(nr, r.l, r.t, r.r, wr.t); Draw(nr, cur.prev) END;
							(* calculate bottom rectangle *)
							IF wr.b < r.b THEN Rect.SetRect(nr, r.l, wr.b, r.r, r.b); Draw(nr, cur.prev) END;
							(* calculate left rectangle *)
							IF wr.l > r.l THEN Rect.SetRect(nr, r.l, MAX(r.t, wr.t), wr.l, MIN(r.b, wr.b)); Draw(nr, cur.prev) END;
							(* calculate left rectangle *)
							IF wr.r < r.r THEN Rect.SetRect(nr, wr.r, MAX(r.t, wr.t), r.r, MIN(r.b, wr.b)); Draw(nr, cur.prev) END;
							(* calculate overlapping *)
							nr := r; Rect.ClipRect(nr, wr);
							IF ~Rect.RectEmpty(nr) THEN InternalDraw(nr, cur) END
						ELSE Draw(r, cur.prev)
						END
					ELSE InternalDraw(r, cur)
					END
				ELSE
					Draw(r, cur.prev);
				END;
			END
		END Draw;

	END ViewPort;

	DirtyQ = OBJECT
	VAR
		dirtyHead, dirtyTail : LONGINT;
		dirtyBuf : ARRAY DirtyBufSize OF Rectangle;
		overflow : BOOLEAN;

		(* Between a call to Has and a call to Get no other process may do a Get *)
		PROCEDURE Has():BOOLEAN;
		BEGIN
			RETURN (dirtyHead # dirtyTail)
		END Has;

		PROCEDURE Get(VAR r : Rectangle);
		BEGIN {EXCLUSIVE}
			AWAIT((dirtyHead # dirtyTail));
			r := dirtyBuf[dirtyHead];
			dirtyHead := (dirtyHead + 1) MOD DirtyBufSize
		END Get;

		PROCEDURE Add(VAR r : Rectangle);
		VAR t : Rectangle; i: LONGINT;
		BEGIN {EXCLUSIVE}
			IF (dirtyTail + 1) MOD DirtyBufSize = dirtyHead THEN
				KernelLog.Enter; KernelLog.String("WindowManager: Buffer Full"); KernelLog.Exit;
				overflow := TRUE; t := r; i := dirtyHead;
				WHILE i # dirtyTail DO Rect.ExtendRect(t, dirtyBuf[i]);
					i := (i + 1) MOD DirtyBufSize
				END;
				dirtyHead := 0; dirtyBuf[0] := t; dirtyTail := 1;
			ELSE
				dirtyBuf[dirtyTail] := r;
				dirtyTail := (dirtyTail + 1) MOD DirtyBufSize
			END
		END Add;

	END DirtyQ;

	UnhitableWindow = OBJECT(WM.BufferWindow);
		PROCEDURE IsHit*(x, y : LONGINT) : BOOLEAN;
		BEGIN
			RETURN FALSE
		END IsHit;
	END UnhitableWindow;

	WindowManager* = OBJECT (WM.WindowManager)
	VAR
		top, bottom : Window; (* top is always present and is the pointer, bottom is always present and is the background *)
		dirtyQ : DirtyQ;
		patches : ARRAY CombineLookahead OF Rectangle;

		running : BOOLEAN;
		views : WM.ViewPort;

		(* pointer handling *)
		kdprev : LONGINT;
		pointerKeys : SET;
		(* used by CheckPointerImg *)
		pointerOwner : Window;
		pointerX, pointerY : LONGINT;
		pointerInfo : WM.PointerInfo;

		(* focus *)
		focusOwner : Window;
		fifi : Fifi;

		(* drag & drop *)
		dragging : BOOLEAN;
		dragImage : Graphics.Image;
		dragCursor : UnhitableWindow;
		dragInfo : WM.DragInfo;
		dragSender : Window;

		PROCEDURE &New*;
		VAR pointer  : WM.BufferWindow; bg : DW.BackWindow;
		BEGIN
			Init;
			NEW(fifi, 4000);
			NEW(dirtyQ);
			NEW(pointer, 30, 30, TRUE); pointer.useAlpha := TRUE;
			top := pointer; top.flags := { WM.FlagStayOnTop, WM.FlagNonDispatched, WM.FlagHidden };
			NEW(bg,0); bg.manager := SELF;
			bottom := bg; bottom.next := top; top.prev := bottom;
			bg.flags := {WM.FlagHidden};
			SetWindowTitle(top, WM.NewString("Mouse Cursor"));
			SetWindowTitle(bottom, WM.NewString("Old background"));
			decorate := DefaultDecorator;
		END New;

		PROCEDURE ShutDown*;
		VAR rect: Rectangle;
		BEGIN
			lock.AcquireWrite;
			ShutDown^; fifi.Cleanup;
			WHILE bottom.next # top DO Remove(bottom.next) END;
			running := FALSE;
			dirtyQ.Add(rect); (* wake up and die *)
			lock.ReleaseWrite
		END ShutDown;

		PROCEDURE CheckChain*(details : BOOLEAN);
		VAR cur : Window; title : Strings.String;
		BEGIN
			KernelLog.Enter;
			KernelLog.String("WindowManager.CheckChain: Bottom up..."); KernelLog.Ln;
			cur := bottom;
			WHILE cur # NIL DO
				KernelLog.String("ID "); KernelLog.Int(cur.id, 0); KernelLog.String(": ");
				IF (cur IS DW.TopWindow) THEN KernelLog.String("[T]");
				ELSIF (cur IS DW.LeftWindow) THEN KernelLog.String("[L]");
				ELSIF (cur IS DW.RightWindow) THEN KernelLog.String("[R]");
				ELSIF (cur IS DW.BottomWindow) THEN KernelLog.String("[B]");
				ELSIF (cur IS DW.BackWindow) THEN
					KernelLog.String("[Back:");
					title := GetWindowTitle(cur);
					IF title # NIL THEN KernelLog.String(title^); ELSE KernelLog.String("NIL"); END;
					KernelLog.String("]");
				ELSIF (cur IS DW.DecorWindow) THEN KernelLog.String("[Decor]");
				ELSE
					title := GetWindowTitle(cur);
					IF title # NIL THEN KernelLog.String(title^) ELSE KernelLog.String("[NIL]") END;
				END;
				IF details THEN
					IF (cur.master # NIL) THEN
						KernelLog.String(" M={"); KernelLog.Int(cur.master.id, 0); KernelLog.String("}");
					END;
					KernelLog.String(" (");
					KernelLog.Bits(cur.flags, 0, 10);
					KernelLog.String(")"); KernelLog.Ln;
				END;
				KernelLog.String("-->");
				cur := cur.next
			END;
			KernelLog.String("NIL"); KernelLog.Ln;
			KernelLog.Exit;
		END CheckChain;

		PROCEDURE InsertAfter(old, new : Window);
		BEGIN
			ASSERT(lock.HasWriteLock());
			new.next := old.next;
			new.prev := old;
			old.next := new;
			new.next.prev := new
		END InsertAfter;

		(* below mouse *)
		PROCEDURE FindTopWindow(stayontop : BOOLEAN) : Window;
		VAR cur : Window;
		BEGIN
			ASSERT(lock.HasWriteLock());
			cur := top.prev;
			IF ~stayontop THEN
				WHILE (cur.prev # NIL) & (WM.FlagStayOnTop IN cur.flags) DO cur := cur.prev END
			END;
			RETURN cur
		END FindTopWindow;

		PROCEDURE FindBottomWindow(stayOnBottom : BOOLEAN) : Window;
		VAR cur : Window;
		BEGIN
			ASSERT(lock.HasWriteLock());
			cur := bottom;
			IF ~stayOnBottom THEN
				WHILE (cur.next # NIL) & (WM.FlagStayOnBottom IN cur.next.flags) DO cur := cur.next; END;
			END;
			ASSERT(cur # NIL);
			RETURN cur;
		END FindBottomWindow;

		PROCEDURE Broadcast*(VAR m : Messages.Message);
		VAR cur : Window; discard : BOOLEAN;
		BEGIN
			lock.AcquireWrite;
			PreviewMessage(m, discard);
			IF ~discard THEN
				cur := bottom;
				WHILE cur # NIL DO
					IF ~SendMessage(cur, m) THEN KernelLog.String("WindowManager: Broadcast did not reach all windows "); KernelLog.Ln END;
					cur := cur.next
				END;
			END;
			lock.ReleaseWrite
		END Broadcast;

		PROCEDURE Add*(left, top : LONGINT; w : Window; flags : SET);
		VAR plugin : Plugins.Plugin; oldPointerOwner: Window; m: Messages.Message;
		BEGIN
			ASSERT((w.next = NIL) & (w.prev = NIL)); (* window can not be inserted twice *)
			lock.AcquireWrite;
			w.flags := w.flags + flags;
			IF flags * { WM.FlagNonDispatched } = { } THEN NEW(w.sequencer, w.Handle) END;
			IF (flags * { WM.FlagNavigation } # {}) & (w.view = NIL) THEN
				plugin := viewRegistry.Get("");
				IF (plugin # NIL) & (plugin IS WM.ViewPort) THEN w.view := plugin (WM.ViewPort); END;
			END;
			Rect.MoveRel(w.bounds, left - w.bounds.l, top - w.bounds.t);
			InsertAfter(FindTopWindow(WM.FlagStayOnTop IN flags), w);
			w.manager := SELF;
			IF (flags * { WM.FlagFrame } # { }) & (decorate # NIL) THEN decorate(w) END;
			oldPointerOwner := GetPositionOwnerIntern(pointerX, pointerY, NIL);
			AddVisibleDirty(w, w.bounds);
			IF oldPointerOwner = NIL THEN
				pointerOwner := GetPositionOwnerIntern(pointerX, pointerY, NIL);
			END;
			CheckPointerImage; (* maybe some other window got below the cursor *)
	
			m.sender:=w; m.msgType := Messages.MsgInvalidate; m.msgSubType := Messages.MsgSubAll;
			IF (w.sequencer#NIL) & w.sequencer.Add(m) THEN END; (* Invalidate window contents when first put on display. *)
			
			lock.ReleaseWrite;
			WM.IncWTimestamp;
		END Add;

		PROCEDURE InternalRemove(w : Window);
		VAR rect : Rect.Rectangle;
		BEGIN
			ASSERT(lock.HasWriteLock());
			IF w.prev # NIL THEN w.prev.next := w.next END;
			IF w.next # NIL THEN w.next.prev := w.prev END;
			w.prev := NIL; w.next := NIL; (* some application programmers tend to remove a window more than once *)
			IF (WM.FlagNavigation IN w.flags) & (w.view # NIL) & (w.view IS ViewPort) THEN
				rect := w.view(ViewPort).GetWMCoordinates(w.bounds);
				dirtyQ.Add(rect);
			ELSE
				dirtyQ.Add(w.bounds)
			END;
		END InternalRemove;

		PROCEDURE Remove*(w : Window);
		VAR dl : WM.DecorList; p : Window;
		BEGIN
			lock.AcquireWrite;
			p := GetPrev(w);
			InternalRemove(w);
			dl := w.decor; WHILE dl # NIL DO InternalRemove(dl.w); (* dl.w.manager := NIL; *) (* fof: caused a trap in MainMenu.Window.SetOriginator while switching the skin *) dl := dl.next END;
			w.decor := NIL;
			IF w.sequencer # NIL THEN w.sequencer.Stop END;
			(* w.manager := NIL; *) (* fof: caused a trap in MainMenu.Window.SetOriginator while switching skin *)
			w.next := NIL; w.prev := NIL;
			IF (w = focusOwner) & (p # NIL) THEN SetFocus(p) END;
			IF pointerKeys = {} THEN (* otherwise the pointerOwner must remain *)
				pointerOwner := GetPositionOwnerIntern(pointerX, pointerY, NIL);
			END;
			CheckPointerImage; (* maybe some other window got below the cursor *)
			lock.ReleaseWrite;
			WM.IncWTimestamp;
		END Remove;

		PROCEDURE ToFront*(x : Window);
		VAR dl : WM.DecorList;
		BEGIN
			IF x = bottom THEN RETURN END;
			IF x.flags * { WM.FlagStayOnBottom } # { } THEN RETURN END;
			lock.AcquireWrite;
			IF x.flags * { WM.FlagDecorWindow } # { } THEN IF x.master # NIL THEN ToFront(x.master) END
			ELSE
				InternalRemove(x);
				InsertAfter(FindTopWindow(WM.FlagStayOnTop IN x.flags), x); AddVisibleDirty(x, x.bounds);
				dl := x.decor; WHILE dl # NIL DO InternalRemove(dl.w); InsertAfter(x, dl.w); AddVisibleDirty(dl.w, dl.w.bounds); dl := dl.next END
			END;
			CheckPointerImage; (* maybe some other window got below the cursor *)
			lock.ReleaseWrite
		END ToFront;

		PROCEDURE ToBack*(x : Window);
		VAR dl : WM.DecorList; t : Window;
		BEGIN
			lock.AcquireWrite;
			IF x.flags * { WM.FlagDecorWindow } # { } THEN IF x.master # NIL THEN ToBack(x.master) END
			ELSE
				InternalRemove(x);
				IF (WM.FlagStayOnTop IN x.flags) THEN
					t := FindTopWindow(FALSE);
				ELSE
					t := FindBottomWindow(WM.FlagStayOnBottom IN x.flags);
				END;
				InsertAfter(t, x); AddVisibleDirty(x, x.bounds);
				dl := x.decor; WHILE dl # NIL DO InternalRemove(dl.w); InsertAfter(x, dl.w); AddVisibleDirty(dl.w, dl.w.bounds); dl := dl.next END
			END;
			CheckPointerImage; (* maybe some other window got below the cursor *)
			lock.ReleaseWrite
		END ToBack;

		PROCEDURE SetWindowFlag*(w : Window; flag : LONGINT; include :  BOOLEAN);
		VAR flagChanged, isAdded : BOOLEAN;

			PROCEDURE SetFlagInternal(w : Window; flag : LONGINT; include : BOOLEAN);
			VAR dl : WM.DecorList;
			BEGIN
				IF include THEN INCL(w.flags, flag); ELSE EXCL(w.flags, flag); END;
				dl := w.decor;
				WHILE (dl # NIL) DO
					IF include THEN INCL(dl.w.flags, flag); ELSE EXCL(dl.w.flags, flag); END;
					dl := dl.next;
				END;
			END SetFlagInternal;

			PROCEDURE AddDecorWindows(w : Window);
			BEGIN
				IF (decorate # NIL) THEN
					decorate(w);
					pointerOwner := GetPositionOwnerIntern(pointerX, pointerY, NIL);
					CheckPointerImage; (* maybe some other window got below the cursor *)
				END;
			END AddDecorWindows;

			PROCEDURE RemoveDecorWindows(w : Window);
			VAR dl : WM.DecorList;
			BEGIN
				dl := w.decor;
				WHILE (dl # NIL) DO
					InternalRemove(dl.w);
					dl.w.manager := NIL;  dl.w.master := NIL;
					dl := dl.next;
				END;
				w.decor := NIL;
				RefreshViews;
			END RemoveDecorWindows;

		BEGIN
			SetWindowFlag^(w, flag, include);
			lock.AcquireWrite;
			IF (WM.FlagDecorWindow IN w.flags) THEN
				w := w.master;
				IF (w = NIL) THEN lock.ReleaseWrite; RETURN; END;
			END;
			flagChanged := (include # (flag IN w.flags));
			IF flagChanged THEN
				isAdded := (w.next # NIL) & (w.prev # NIL);
				CASE flag OF
					|WM.FlagFrame:
						IF include THEN
							INCL(w.flags, flag);
							IF isAdded THEN AddDecorWindows(w); END;
						ELSE
							EXCL(w.flags, flag);
							IF isAdded THEN RemoveDecorWindows(w); END;
						END;
					|WM.FlagStayOnTop:
						IF include THEN
							EXCL(w.flags, WM.FlagStayOnBottom);
							SetFlagInternal(w, flag, TRUE);
							IF isAdded THEN ToFront(w); END;
						ELSE
							SetFlagInternal(w, flag, FALSE);
							IF isAdded THEN ToBack(w); END;
						END;
					|WM.FlagStayOnBottom:
						IF include THEN
							SetFlagInternal(w, WM.FlagStayOnTop, FALSE);
							INCL(w.flags, flag);
							IF isAdded THEN ToBack(w); END;
						ELSE
							EXCL(w.flags, flag);
							IF isAdded THEN ToFront(w); END;
						END;
					|WM.FlagHidden:
						IF include THEN INCL(w.flags, flag); ELSE EXCL(w.flags, flag); END;
				ELSE
					lock.ReleaseWrite; HALT(99);
				END;
			END;
			lock.ReleaseWrite;
			IF flagChanged THEN WM.IncOTimestamp; END;
		END SetWindowFlag;

		PROCEDURE SetWindowPos*(w : Window; x, y : LONGINT);
		VAR rect : Rectangle; dx, dy : LONGINT; cur : WM.DecorList;
		BEGIN
			IF w = NIL THEN RETURN END;
			lock.AcquireWrite;
			dx := x - w.bounds.l; dy := y - w.bounds.t;
			IF (w.master # NIL) THEN w := w.master END;
			rect := w.bounds; Rect.MoveRel(w.bounds, dx, dy); Rect.ExtendRect(rect, w.bounds);
			cur := w.decor;
			WHILE cur # NIL DO
				Rect.ExtendRect(rect, cur.w.bounds);Rect.MoveRel(cur.w.bounds, dx, dy); Rect.ExtendRect(rect, cur.w.bounds);
				cur := cur.next
			END;
			CheckPointerImage; (* maybe some other window got below the cursor *)
			AddVisibleDirty(w, rect); (* assuming decor windows USE alpha *)
			lock.ReleaseWrite;
			WM.ResetNextPosition;
		END SetWindowPos;

		PROCEDURE SetWindowSize*(w : Window; VAR width, height : LONGINT);
		VAR
			rect : Rectangle;
			cw, ch, t, nw : LONGINT;

			PROCEDURE Set(win : Window; w, h  : LONGINT);
			BEGIN
				Rect.ExtendRect(rect, win.bounds);
				win.Resizing(w, h); win.bounds.r := win.bounds.l + w; win.bounds.b := win.bounds.t + h;
				Rect.ExtendRect(rect, win.bounds)
			END Set;

		BEGIN
			lock.AcquireWrite;
			rect := w.bounds;
			cw := w.GetWidth(); ch := w.GetHeight();
			w.Resizing(width, height);
			IF (cw # width) OR (ch # height) THEN
				w.bounds.r := w.bounds.l + width;
				w.bounds.b := w.bounds.t + height;
				IF cw # width THEN
					IF w.topW # NIL THEN
						nw := width + (w.topW.GetWidth() - cw);
						t := w.topW.GetHeight(); Set(w.topW, nw, t);
					END;
					IF w.bottomW # NIL THEN
						nw := width + (w.bottomW.GetWidth() - cw);
						t := w.bottomW.GetHeight(); Set(w.bottomW, nw, t)
					END;
					IF w.rightW # NIL THEN
						Rect.ExtendRect(rect, w.rightW.bounds);
						Rect.MoveRel(w.rightW.bounds, width - cw, 0);
						Rect.ExtendRect(rect, w.rightW.bounds)
					END
				END;
				IF ch # height THEN
					IF w.leftW # NIL THEN
						nw := height + (w.leftW.GetHeight() - ch);
						t := w.leftW.GetWidth(); Set(w.leftW, t, nw)
					END;
					IF w.rightW # NIL THEN
						nw := height + (w.rightW.GetHeight() - ch);
						t := w.rightW.GetWidth(); Set(w.rightW, t, nw)
					END;
					IF w.bottomW # NIL THEN
						Rect.ExtendRect(rect, w.bottomW.bounds);
						Rect.MoveRel(w.bottomW.bounds, 0, height - ch);
						Rect.ExtendRect(rect, w.bottomW.bounds)
					END
				END;
				Rect.ExtendRect(rect, w.bounds);
				IF (WM.FlagNavigation IN w.flags) & (w.view # NIL) & (w.view IS ViewPort) THEN
					rect := w.view(ViewPort).GetWMCoordinates(rect);
				END;
				dirtyQ.Add(rect);
				CheckPointerImage
			END;
			lock.ReleaseWrite
		END SetWindowSize;

	(** View management *)
		(** Add a view *)
		PROCEDURE AddView*(v : WM.ViewPort);
		VAR res : WORD;
		BEGIN
			lock.AcquireWrite;
			v.manager := SELF;
			v.next := views; views := v;
			lock.ReleaseWrite;
			viewRegistry.Add(v, res)
		END AddView;

		(** Add the whole View.range as dirty and cause a redraw *)
		PROCEDURE RefreshView*(v : WM.ViewPort);
		BEGIN
			lock.AcquireWrite;
			v.Refresh(top);
			lock.ReleaseWrite
		END RefreshView;

		(* Redraw all view ranges *)
		PROCEDURE RefreshViews;
		VAR v : WM.ViewPort;
		BEGIN
			lock.AcquireWrite;
			v := views;
			WHILE (v # NIL) DO v.Refresh(top); v := v.next; END;
			lock.ReleaseWrite;
		END RefreshViews;

		(** RemoveView from windowmanager *)
		PROCEDURE RemoveView*(v : WM.ViewPort);
		VAR cur : WM.ViewPort;
		BEGIN
			IF v = NIL THEN RETURN END;
			lock.AcquireWrite;
			IF v = views THEN views := views.next
			ELSE
				IF views # NIL THEN
					cur := views; WHILE (cur.next # NIL) & (cur.next # v) DO cur := cur.next END;
					IF cur.next = v THEN cur.next := cur.next.next END
				END
			END;
			viewRegistry.Remove(v);
			lock.ReleaseWrite
		END RemoveView;

		PROCEDURE ReplaceBackground*(w : Window) : Window;
		VAR old : Window;
		BEGIN
			lock.AcquireWrite;
			w.manager := SELF;
			old := bottom; bottom := w; bottom.next := old.next; bottom.next.prev := bottom;
			old.next := NIL;
			lock.ReleaseWrite;
			RETURN old
		END ReplaceBackground;

		(** Return the area that is actually occupied *)
		PROCEDURE GetPopulatedArea*(VAR r : Rectangle);
		VAR first: BOOLEAN; cur : Window;
		BEGIN
			lock.AcquireWrite;
			first := TRUE;
			cur := bottom.next;
			WHILE (cur # NIL) & (cur # top) DO
				IF first THEN r := cur.bounds; first := FALSE
				ELSE Rect.ExtendRect(r, cur.bounds)
				END;
				cur := cur.next
			END;
			lock.ReleaseWrite;
		END GetPopulatedArea;

	(** Enumeration *)
		(** Get the first "user" window --> May return NIL if only background and pointer window are installed *)
		(** Must hold lock *)
		PROCEDURE GetFirst*() : Window;
		VAR cur : Window;
		BEGIN
			ASSERT(lock.HasWriteLock());
			cur := bottom; WHILE (cur # NIL) & (cur.master # NIL)  DO cur := cur.next END;
			RETURN cur
		END GetFirst;

		(** Get the window next "user" window on top of cur *)
		PROCEDURE GetNext*(cur : Window) : Window;
		BEGIN
			ASSERT(lock.HasWriteLock());
			IF cur # NIL THEN cur := cur.next END;
			WHILE (cur # NIL) & (cur.master # NIL) DO cur := cur.next END;
			RETURN cur
		END GetNext;

		(** Get the "user" window below cur *)
		PROCEDURE GetPrev*(cur : Window) : Window;
		BEGIN
			ASSERT(lock.HasWriteLock());
			IF cur # NIL THEN cur := cur.prev END;
			WHILE (cur # NIL) & (cur.master # NIL) DO cur := cur.prev END;
			RETURN cur
		END GetPrev;

		(** Set the keyboard focus to the window w *)
		PROCEDURE SetFocus*(w : Window);
		VAR dl : WM.DecorList;

			PROCEDURE SendFocusMessage(dst : Window; has : BOOLEAN);
			VAR m : Messages.Message;
			BEGIN
				m.msgType := Messages.MsgFocus;
				IF ~has THEN m.msgSubType := Messages.MsgSubFocusLost ELSE m.msgSubType := Messages.MsgSubFocusGot END;
				IF ~SendMessage(dst, m) THEN KernelLog.String("Focus message not sent"); KernelLog.Ln END;

				IF ~has THEN m.msgSubType := Messages.MsgSubMasterFocusLost
				ELSE m.msgSubType := Messages.MsgSubMasterFocusGot
				END;
				dl := dst.decor; WHILE dl # NIL DO IF SendMessage(dl.w, m) THEN (* ignore *) END; dl := dl.next END
			END SendFocusMessage;

		BEGIN
			lock.AcquireWrite;
			IF w = focusOwner THEN lock.ReleaseWrite; RETURN END;
			IF w.flags * { WM.FlagNoFocus } = { } THEN
				IF focusOwner # NIL THEN SendFocusMessage(focusOwner, FALSE) END;
				focusOwner := w;
				SendFocusMessage(focusOwner, TRUE)
			ELSE
				IF w.master # NIL THEN SetFocus(w.master) END
			END;
			lock.ReleaseWrite;
			WM.IncOTimestamp;
		END SetFocus;

		(** Return the window at postition x, y in global space. *)
		(** Must hold WM lock *)
		PROCEDURE GetPositionOwnerIntern(x, y : LONGINT; owner : WM.ViewPort) : Window;
		VAR cur : Window; xt, yt : LONGINT; bounds : Rect.Rectangle; ignore : BOOLEAN;
		BEGIN
			lock.AcquireWrite;
			cur := top.prev; (* not the mouse *)
			WHILE cur # NIL DO
				ignore := FALSE;
				IF (WM.FlagNavigation IN cur.flags) THEN
					IF (owner # NIL) & (owner IS ViewPort) & (cur.view = owner) THEN
						bounds := owner(ViewPort).GetWMCoordinates(cur.bounds);
						xt := ENTIER((x - owner(ViewPort).range.l) * owner(ViewPort).fx);
						yt := ENTIER((y - owner(ViewPort).range.t) * owner(ViewPort).fy);
					ELSE
						ignore := TRUE;
					END;
				ELSE
					bounds := cur.bounds;
					xt := x; yt := y;
				END;
				IF ~ignore & Rect.PointInRect(x, y, bounds) THEN
					IF cur.isVisible & cur.IsHit(xt - cur.bounds.l, yt - cur.bounds.t) THEN
						lock.ReleaseWrite;
						RETURN cur
					END
				END;
				cur := cur.prev
			END;
			lock.ReleaseWrite;
			RETURN NIL
		END GetPositionOwnerIntern;

		PROCEDURE GetPositionOwner*(x, y : LONGINT) : Window;
		BEGIN
			RETURN GetPositionOwnerIntern(x, y, NIL);
		END GetPositionOwner;

		(** Adjust pointer to new position / check picture *)
		(** MUST hold wm lock *)
		PROCEDURE CheckPointerImage*;
		VAR rect : Rectangle; pi : WM.PointerInfo;
		BEGIN
			lock.AcquireWrite;
			ASSERT(top # NIL);

			IF pointerOwner # NIL THEN
				IF WM.FlagNoPointer IN pointerOwner.flags THEN pi := pointerNull ELSE pi := pointerOwner.pointerInfo END;
			(*ELSIF WM.FlagNoPointer IN top.flags THEN pi := pointerNull; pointerInfo := pi; *)
			ELSE pi := NIL
			END;

			IF pi = NIL THEN pi := pointerStandard END; IF pointerInfo = NIL THEN pointerInfo := pointerStandard END;

			IF (pi # pointerInfo) OR ((pointerX # top.bounds.l - pointerInfo.hotX) OR (pointerY # top.bounds.t - pointerInfo.hotY)) THEN
				rect := top.bounds;

				IF (pi.img # NIL) & (top IS WM.BufferWindow) THEN
					top(WM.BufferWindow).img := pi.img;
					top.bounds.l := pointerX - pi.hotX;
					top.bounds.t := pointerY - pi.hotY;
					top.bounds.r := top.bounds.l + top(WM.BufferWindow).img.width;
					top.bounds.b := top.bounds.t + top(WM.BufferWindow).img.height
				ELSE
					top.bounds.l := pointerX;
					top.bounds.t := pointerY;
					top.bounds.r := top.bounds.l;
					top.bounds.b := top.bounds.t
				END;

				dirtyQ.Add(top.bounds);
				dirtyQ.Add(rect);
				(* the dirty q handling will merge the rectangles if beneficial. Doing it here results in potential large area screen updates *)

				pointerInfo := pi
			END;
			lock.ReleaseWrite
		END CheckPointerImage;

		PROCEDURE GetFocusOwner*() : Window;
		BEGIN
			RETURN focusOwner;
		END GetFocusOwner;

		PROCEDURE PointerEvent(VAR msg : Messages.Message);
		VAR
			newOwner : Window;
			view : ViewPort;
			kd, i : LONGINT;
			m : Messages.Message;
			keys : SET;

				PROCEDURE MouseMessage(sub:LONGINT);
				VAR bounds : Rect.Rectangle; vp : ViewPort;
				BEGIN
					(* do not translate to local coordinates here: must be done by sequencer! *)
					IF (pointerOwner # NIL)  THEN
						m.msgType := Messages.MsgPointer;
						m.msgSubType := sub;
						IF (WM.FlagNavigation IN pointerOwner.flags) THEN
							IF (pointerOwner.view # NIL) & (pointerOwner.view IS ViewPort) THEN
								vp := pointerOwner.view (ViewPort);
								bounds := pointerOwner.bounds;
								m.x := ENTIER((msg.x - vp.range.l) * vp.fx);
								m.y := ENTIER((msg.y - vp.range.t) * vp.fy);
							END;
						ELSE
							bounds := pointerOwner.bounds;
							m.x := msg.x; m.y := msg.y;
						END;
						m.flags := keys;
						IF pointerOwner.sequencer # NIL THEN IF ~pointerOwner.sequencer.Add(m) THEN END (* ignore missed mouse messages *)
						ELSE pointerOwner.Handle(m)
						END
					END
				END MouseMessage;

				PROCEDURE DragMessage(sub : LONGINT; dst : Window);
				BEGIN
					IF (dst # NIL)  THEN
						m.msgType := Messages.MsgDrag;
						m.msgSubType := sub;
						m.sender := dragSender;
						m.ext := dragInfo;
						m.x := msg.x - dst.bounds.l; m.y := msg.y - dst.bounds.t;
						IF dst.sequencer # NIL THEN IF ~dst.sequencer.Add(m) THEN END (* ignore missed drag messages *)
						END
					END
				END DragMessage;

				PROCEDURE DragAbortMessage;
				BEGIN
					IF (dragInfo # NIL) & (dragInfo.onReject # NIL) THEN dragInfo.onReject(SELF, dragInfo) END
				END DragAbortMessage;

				PROCEDURE RemoveDragCursor;
				BEGIN
					IF dragCursor # NIL THEN Remove(dragCursor) END;
				END RemoveDragCursor;

		BEGIN
			ASSERT(sequencer.IsCallFromSequencer());
			IF ~running THEN RETURN END;
			IF (msg.originator # NIL) & (msg.originator IS ViewPort) THEN
				view := msg.originator (ViewPort);
			ELSE
				view := NIL;
			END;
			m.originator := sequencer.GetOriginator();
			m := msg; keys := msg.flags;
			IF dragging THEN
				IF keys = {} THEN DragMessage(Messages.MsgDragDropped, GetPositionOwnerIntern(msg.x, msg.y, view)); dragging := FALSE
				ELSIF keys * {0, 1, 2} = {0, 1, 2} THEN dragging := FALSE; (* abort drag *)
					(* fixup key state *)
					kd := 0; FOR i := 0 TO 31 DO IF i IN keys THEN INC(kd) END END;
					kdprev := kd; pointerKeys := keys;
					DragAbortMessage
				ELSE DragMessage(Messages.MsgDragOver, GetPositionOwnerIntern(msg.x, msg.y, view))
				END;
				IF dragging THEN SetWindowPos(dragCursor, msg.x+dragInfo.offsetX, msg.y+dragInfo.offsetY)
				ELSE RemoveDragCursor
				END;
				pointerX := msg.x; pointerY := msg.y; CheckPointerImage;
				IF dragging THEN RETURN END
			END;

			(* if no keys are pressed, the new pointer owner is the position owner *)
			IF (keys = { })THEN newOwner := GetPositionOwnerIntern(msg.x, msg.y, view)END;
			IF  newOwner = NIL THEN newOwner := pointerOwner END;
			(* keys changed *)
			IF keys # pointerKeys THEN
				kd := 0; FOR i := 0 TO 31 DO IF i IN keys THEN INC(kd) END END;
				(* the number of pressed keys is less --> one is up *)
				IF kd < kdprev THEN MouseMessage(Messages.MsgSubPointerUp)
				ELSE SetFocus(newOwner); MouseMessage(Messages.MsgSubPointerDown); (* no check --> keys did change *)
				END;
				kdprev := kd; pointerKeys := keys
			END;

			IF newOwner # pointerOwner THEN MouseMessage(Messages.MsgSubPointerLeave); pointerOwner := newOwner END;
			pointerX := msg.x; pointerY := msg.y;
			IF pointerOwner # NIL THEN CheckPointerImage; MouseMessage(Messages.MsgSubPointerMove) END
		END PointerEvent;

		PROCEDURE KeyEvent*(VAR m : Messages.Message);
		VAR p : Window;
		BEGIN
			ASSERT(sequencer.IsCallFromSequencer());
			IF ~running THEN RETURN END;
			IF (focusOwner # NIL) THEN
				IF (m.flags * Inputs.Alt # {}) & (m.y = 0FF09H) THEN
					p := GetPrev(focusOwner);
					IF p # NIL THEN ToFront(p); SetFocus(p) END
				ELSE
		 			IF focusOwner.sequencer # NIL THEN IF ~focusOwner.sequencer.Add(m) THEN END (* ignore keyboard message *)
			 		ELSE focusOwner.Handle(m)
			 		END
			 	END
		 	END
		END KeyEvent;

		PROCEDURE HandleInternal*(VAR msg : Messages.Message);
		BEGIN
			HandleInternal^(msg);
			IF msg.msgType = Messages.MsgKey THEN KeyEvent(msg)
			ELSIF msg.msgType = Messages.MsgPointer THEN PointerEvent(msg)
			END
		END HandleInternal;

		PROCEDURE StartDrag*(w : Window; sender, data : ANY; img : Graphics.Image; offsetX, offsetY: LONGINT; onAccept, onReject : Messages.CompCommand) : BOOLEAN;
		VAR result : BOOLEAN;

			PROCEDURE AddDragCursor;
			VAR w, h : LONGINT;
			BEGIN
				NEW(dragCursor, 1, 1, TRUE); w := 1; h := 1;
				IF dragImage # NIL THEN
					dragCursor.img := dragImage; w:= dragImage.width; h := dragImage.height
				END;
				Add(pointerX+offsetX, pointerY+offsetY, dragCursor, { WM.FlagStayOnTop, WM.FlagNonDispatched, WM.FlagHidden });
				SetWindowSize(dragCursor, w, h)
			END AddDragCursor;

		BEGIN
			result := FALSE;
			lock.AcquireWrite;
			IF (w = pointerOwner) & ~dragging THEN
				result := TRUE;
				dragging := TRUE;
				dragImage := img; dragSender := w;
				NEW(dragInfo);
				dragInfo.sender := sender; dragInfo.data := data;
				dragInfo.onAccept := onAccept; dragInfo.onReject := onReject;
				dragInfo.offsetX := offsetX; dragInfo.offsetY := offsetY;
				AddDragCursor
			END;
			lock.ReleaseWrite;
			RETURN result
		END StartDrag;

		(** a pointer button must be pressed *)
		PROCEDURE TransferPointer*(to : Window) : BOOLEAN;
		VAR ok : BOOLEAN;
		BEGIN
			lock.AcquireWrite;
			ok := FALSE;
			IF pointerKeys # {}  THEN
				ok := TRUE;
				pointerOwner := to; CheckPointerImage;
			END;
			lock.ReleaseWrite;
			RETURN ok
		END TransferPointer;

		(** Add a region to be refreshed *)
		PROCEDURE AddDirty*(VAR rect:Rectangle);
		BEGIN
			dirtyQ.Add(rect)
		END AddDirty;

		(** Add a region to be refreshed, if visible through windows w and above *)
		PROCEDURE AddVisibleDirty*(w : Window; rect : Rectangle);
		VAR temp : Rect.Rectangle;

			(* Subtract hidden regions --> i.e. pass on non hidden parts *)
			PROCEDURE Sub(x : Window; VAR r : Rectangle);
			VAR nr : Rectangle; bounds : Rect.Rectangle;
			BEGIN
				IF Rect.RectEmpty(r) THEN RETURN END;

				IF (x = NIL) OR (x = top) THEN
					(* there is nothing in front of this rectangle part --> must draw *)
					dirtyQ.Add(r);
					RETURN
				END;

				IF ~x.useAlpha & x.isVisible THEN
					IF (WM.FlagNavigation IN x.flags) & (x.view # NIL) & (x.view IS ViewPort) THEN
						bounds := w.view(ViewPort).GetWMCoordinates(x.bounds);
					ELSE
						bounds := x.bounds;
					END;
					IF Rect.IsContained(bounds, r) THEN
						(* the remaining rect is completely covered by non alpha window *)
						RETURN
					ELSIF Rect.Intersect(bounds, r) THEN  (* the rectangle intersects with the window x in front *)
						(* calculate top rectangle *)
						IF bounds.t > r.t THEN Rect.SetRect(nr, r.l, r.t, r.r, bounds.t); Sub(x.next, nr) END;
						(* calculate bottom rectangle *)
						IF bounds.b < r.b THEN Rect.SetRect(nr, r.l, bounds.b, r.r, r.b);Sub(x.next, nr) END;
						(* calculate left rectangle *)
						IF bounds.l > r.l THEN Rect.SetRect(nr, r.l, MAX(r.t, bounds.t), bounds.l, MIN(r.b, bounds.b)); Sub(x.next, nr) END;
						(* calculate right rectangle *)
						IF bounds.r < r.r THEN Rect.SetRect(nr, bounds.r, MAX(r.t, bounds.t), r.r, MIN(r.b, bounds.b)); Sub(x.next, nr) END
					ELSE (* the window x is not in front *)
						Sub(x.next, r)
					END
				ELSE (* the window x uses alpha *)
					Sub(x.next, r)
				END
			END Sub;

		BEGIN
			lock.AcquireWrite;
			IF (WM.FlagNavigation IN w.flags) THEN
				IF (w.view # NIL) & (w.view IS ViewPort) THEN
					temp := w.view(ViewPort).GetWMCoordinates(rect);
				END;
			ELSE
				temp := rect;
			END;
			Sub(w.next, temp);
			lock.ReleaseWrite
		END AddVisibleDirty;

		PROCEDURE RedrawDirty;
		VAR r, m:Rectangle;
			i, na, oa, nofPatches:LONGINT;
			found : BOOLEAN; cv : WM.ViewPort;
		BEGIN
			dirtyQ.Get(patches[0]);
			nofPatches := 1;
			lock.AcquireWrite;
			WHILE dirtyQ.Has() DO
				dirtyQ.Get(r);
				na := Rect.Area(r);
				found := FALSE;
				i := 0; WHILE (i < nofPatches) & ~found DO
					m := patches[i]; oa := Rect.Area(m);
					Rect.ExtendRect(m, r);
					IF Rect.Area(m) <= 2 * (oa+na) THEN
						patches[i] := m; found := TRUE
					END;
					INC(i)
				END;
				IF ~found THEN patches[nofPatches] := r; INC(nofPatches) END;
				IF nofPatches =  CombineLookahead THEN
					(* update Viewports *)
					cv := views;
					WHILE cv # NIL DO
						FOR i := 0 TO nofPatches - 1 DO cv.Update(patches[i], top) END;
						cv := cv.next
					END;
					nofPatches := 0
				END;
			END;

			(* update Viewports *)
			cv := views;
			WHILE cv # NIL DO
				FOR i := 0 TO nofPatches - 1 DO
					cv.Update(patches[i], top);  (* tester.DrawRect(patches[i], 0FF10H); *)
				END;
				cv := cv.next
			END;
			lock.ReleaseWrite
		END RedrawDirty;

		PROCEDURE DefaultDecorator(w : Window);
		VAR
			top : DW.TopWindow;
			left : DW.LeftWindow;
			right : DW.RightWindow;
			bottom : DW.BottomWindow;
			l, t, r, b : LONGINT;
			th, lw, rw, bh : LONGINT;

			PROCEDURE InitW(n : Window);
			BEGIN
				n.manager := SELF; n.flags := n.flags + {WM.FlagNoFocus, WM.FlagHidden};
				IF WM.FlagStayOnTop IN w.flags THEN INCL(n.flags, WM.FlagStayOnTop) END;
				IF WM.FlagStayOnBottom IN w.flags THEN INCL(n.flags, WM.FlagStayOnBottom); END;
				IF WM.FlagNavigation IN w.flags THEN
					n.view := w.view;
					INCL(n.flags, WM.FlagNavigation);
				END;
				IF WM.FlagNoResizing IN w.flags THEN INCL(n.flags, WM.FlagNoResizing); END;
				InsertAfter(w, n); AddDecorWindow(w, n);
				AddVisibleDirty(n, n.bounds);
				n.StyleChanged
			END InitW;

		BEGIN
			ASSERT(lock.HasWriteLock());

			NEW(top, 0, 0, FALSE);NEW(left, 0, 0, FALSE); NEW(right, 0, 0, FALSE); NEW(bottom, 0, 0, FALSE);
			th := 10; lw := 2; rw := 2; bh := 2;
			l := w.bounds.l; t := w.bounds.t; r := w.bounds.r; b := w.bounds.b;

			top.useBitmaps := FALSE; left.useBitmaps := FALSE;
			right.useBitmaps := FALSE; bottom.useBitmaps := FALSE;
			(* Top *)
			top.bounds := Rect.MakeRect(l - lw, t - th, r + rw, t);
			top.mode := 0; top.distXY := XYResizeHandleSize;
			top.SetPointerInfo(pointerMove); top.vertical := FALSE;
			top.threshold := 110; top.focusthreshold := 200;

			(* Left *)
			left.bounds := Rect.MakeRect(l - lw, t, l, b);
			left.mode := 3; left.distXY := XYResizeHandleSize; left.vertical := TRUE;
			left.threshold := 110; left.focusthreshold := 200;

			(* Right *)
			right.bounds := Rect.MakeRect(r + 1, t, r + 1 + rw, b);
			right.mode := 1; right.distXY := XYResizeHandleSize; right.vertical := TRUE;
			right.threshold := 110; right.focusthreshold := 200;

			(* Bottom *)
			bottom.bounds := Rect.MakeRect(l - lw, b + 1, r + rw, b + 1 + bh);
			bottom.mode := 2; bottom.distXY :=   lw + XYResizeHandleSize; bottom.vertical := FALSE;
			bottom.threshold := 110; bottom.focusthreshold := 200;

			(* Init decor windows *)
			InitW(top); w.topW := top; top.useAlpha := TRUE;
			InitW(left); w.leftW := left; left.useAlpha := TRUE;
			InitW(right); w.rightW := right; right.useAlpha := TRUE;
			InitW(bottom); w.bottomW := bottom; bottom.useAlpha := TRUE;
		END DefaultDecorator;

		PROCEDURE Touch;
		BEGIN
			lock.AcquireWrite;
			fifi.Reset;
			lock.ReleaseWrite
		END Touch;

	BEGIN {ACTIVE, SAFE}
		IF running THEN KernelLog.String("WindowManager: RESTARTED"); lock.Reset; CheckChain(FALSE) END;
		running := TRUE;
		WHILE running DO RedrawDirty END;
		KernelLog.String("WindowManager: Window manager closed"); KernelLog.Ln;
	END WindowManager;

VAR
	DoubleClick: LONGINT;
TYPE
	MouseObj = OBJECT (Inputs.Sink)
	VAR
		view : ViewPort;
		x, y, z : LONGINT;
		threshold, speedup: LONGINT;
		enableMMEmulation : BOOLEAN;

		(* double click support *)
		lastTime, lastX, lastY: LONGINT;
		prevKeys: SET; inDoubleClick: BOOLEAN;
	(*CONST
		DoubleClick = 400 (* ms *);*)

		PROCEDURE &Init*(t, s:LONGINT);
		BEGIN
			Inputs.mouse.Register(SELF);
			threshold := t; speedup := s;
			enableMMEmulation := TRUE;
			prevKeys := {};
			lastTime := Kernel.GetTicks()-DoubleClick;
			inDoubleClick := FALSE;
		END Init;

		PROCEDURE Handle*(VAR msg: Inputs.Message);
		VAR dx, dy, dz, nx, ny, nz: LONGINT; modifierFlags : SET; time: LONGINT;
		BEGIN {EXCLUSIVE}
			IF (msg IS Inputs.MouseMsg) THEN
				WITH msg: Inputs.MouseMsg DO
					dx := msg.dx; dy := msg.dy;
					IF (ABS(dx) > threshold) OR (ABS(dy) > threshold) THEN
						dx := dx*speedup DIV 10; dy := dy*speedup DIV 10
					END;
					INC(x, dx); INC(y, dy); INC(z, msg.dz);
					IF view = NIL THEN RETURN END;
					IF 1 IN msg.keys THEN enableMMEmulation := FALSE END;
					IF enableMMEmulation & (0 IN msg.keys) THEN
						view.GetKeyState(modifierFlags);
						IF (Inputs.Ctrl * modifierFlags # {}) THEN msg.keys := msg.keys - {0} + {1}; END;
					END;
					Bound(x, 0, view.backbuffer.width - 1); Bound(y, 0, view.backbuffer.height - 1);
					view.PointerEvent(x, y, z, msg.dx, msg.dy, msg.dz, msg.keys)
				END
			ELSIF (msg IS Inputs.AbsMouseMsg) THEN

				WITH msg: Inputs.AbsMouseMsg DO
					IF Displays.reverse THEN
						nx := view.display.width-msg.x-1;
						ny := view.display.height-msg.y-1;
						dx := -msg.dx;
						dy := -msg.dy;
					ELSE
						nx := msg.x;  
						ny := msg.y;  
						dx := msg.dx;
						dy := msg.dy;
					END;
					nz := msg.z; dz := msg.dz;
					IF (DoubleClick > 0) & (msg.keys = {0}) & (prevKeys = {}) THEN
						time := Kernel.GetTicks();
						IF (time - lastTime < DoubleClick) & (ABS(nx-lastX) < 3) & (ABS(ny-lastY) <3) THEN
							msg.keys := {1}; lastTime := time-DoubleClick;
							inDoubleClick := TRUE;
						ELSE
							lastTime := time; lastX := nx; lastY := ny;
						END;
					ELSIF inDoubleClick & (msg.keys = {0}) THEN 
						msg.keys := {1}; 
						(* no change after double click -- avoid sending a click event right after a double click event *)
					ELSE
						inDoubleClick := FALSE;
					END;
					prevKeys := msg.keys ;

					IF dx # 0 THEN INC( x, dx );
					ELSE dx := nx-x; x:= nx;
					END;
					IF dy # 0 THEN INC( y, dy );  
					ELSE dy := ny - y;  y := ny;
					END;
					IF dz # 0 THEN INC( z, dz );  
					(*ELSE dz := nz - z; z := nz;*)
					END;

					IF (ABS( dx ) > threshold) OR (ABS( dy ) > threshold) THEN dx := dx * speedup DIV 10;  dy := dy * speedup DIV 10
					END;
					IF 1 IN msg.keys THEN enableMMEmulation := FALSE END;
					IF view = NIL THEN RETURN END;
					IF enableMMEmulation & (0 IN msg.keys) THEN
						view.GetKeyState(modifierFlags);
						IF (Inputs.Ctrl * modifierFlags # {}) THEN msg.keys := msg.keys - {0} + {1}; END;
					END;
					Bound( x, 0, view.backbuffer.width - 1 );  Bound( y, 0, view.backbuffer.height - 1 );
					view.PointerEvent( x, y, z, dx, dy, dz, msg.keys )
				END;
			END;
		END Handle;

	END MouseObj;

	(** The keyboard handler *)
	KeyboardObj = OBJECT (Inputs.Sink)
	VAR
		view : ViewPort; ch : LONGINT;

		PROCEDURE Handle*(VAR msg: Inputs.Message);
		BEGIN {EXCLUSIVE}
			IF view = NIL THEN RETURN END;
			ch := ORD(msg(Inputs.KeyboardMsg).ch);
			IF (ch >= 128) &(ch <= 155) THEN MapChars(ch) END;
			view.KeyEvent(ch, msg(Inputs.KeyboardMsg).flags, msg(Inputs.KeyboardMsg).keysym)
		END Handle;

		PROCEDURE MapChars(VAR ch : LONGINT);
		BEGIN
			ch := CharToUnicode[ch];
		END MapChars;

		PROCEDURE &Init*;
		BEGIN
			Inputs.keyboard.Register(SELF)
		END Init;

	END KeyboardObj;

	Toucher = OBJECT
	VAR
		timer: Kernel.Timer;
		alive : BOOLEAN;
	BEGIN {ACTIVE}
		alive := TRUE;
		NEW(timer);
		WHILE alive DO
			timer.Sleep(500);
			session.Touch;
		END
	END Toucher;

	Fifi = OBJECT
	VAR
		timer: Kernel.Timer; delay: LONGINT; time: Kernel.MilliTimer; alive, done: BOOLEAN;

		PROCEDURE Cleanup;
		BEGIN {EXCLUSIVE}
			alive := FALSE;
			timer.Wakeup;
			AWAIT(done)
		END Cleanup;

		PROCEDURE Done;
		BEGIN {EXCLUSIVE}
			done := TRUE
		END Done;

		PROCEDURE Reset;
		BEGIN
			Kernel.SetTimer(time, delay)
		END Reset;

		PROCEDURE &Init*(delay: LONGINT);
		BEGIN
			SELF.delay := delay;
			alive := TRUE; done := FALSE;
			NEW(timer)
		END Init;

	BEGIN {ACTIVE}
		LOOP
			timer.Sleep(delay);
			IF ~alive THEN EXIT END;
			IF Kernel.Expired(time) THEN
				KernelLog.String("Fifi --> "); KernelLog.Ln;
				(* session.DumpLock;*) session.CheckChain(FALSE);
				alive := FALSE
			END
		END;
		Done
	END Fifi;

VAR
	session : WindowManager;
	toucher :Toucher;
	defaultKeyboard : KeyboardObj;
	defaultMouse : MouseObj;
	CharToUnicode: ARRAY 256 OF LONGINT; (** mapping from Oberon character codes to Unicodes **)


PROCEDURE Bound(VAR x:LONGINT; min, max:LONGINT);
BEGIN
	IF x < min THEN x := min ELSE IF x > max THEN x := max END END
END  Bound;

PROCEDURE ClipAtImage(VAR x: Rectangle; img:Raster.Image);
BEGIN
	Bound(x.l, 0, img.width); Bound(x.r, 0, img.width);
	Bound(x.t, 0, img.height); Bound(x.b, 0, img.height)
END ClipAtImage;

PROCEDURE FillSession(wm : WindowManager; bgColor: LONGINT; noPointer: BOOLEAN);
VAR bg : DW.BackWindow; t : Window;
BEGIN
	NEW(bg, bgColor);
	bg.flags := {WM.FlagHidden};
	IF noPointer THEN
		INCL(bg.flags, WM.FlagNoPointer);
	END;
	wm.SetWindowTitle(bg, WM.NewString("New background"));
	Rect.SetRect(bg.bounds, MIN(LONGINT), MIN(LONGINT), MAX(LONGINT), MAX(LONGINT));
	wm.lock.AcquireWrite; t := wm.ReplaceBackground(bg); wm.lock.ReleaseWrite;
END FillSession;

PROCEDURE Replace*(color: LONGINT; noPointer: BOOLEAN);
VAR disp : Plugins.Plugin; view : ViewPort; r : Rectangle; res : WORD;
BEGIN
	disp := Displays.registry.Await("");
	IF (disp(Displays.Display).format = Displays.color8888) THEN
		WM.format := Raster.BGRA8888;
		KernelLog.String("WindowManager: 32-bit color"); KernelLog.Ln;
	ELSIF disp(Displays.Display).format = Displays.color888 THEN
		WM.format := Raster.BGR888;
		KernelLog.String("WindowManager: 24-bit color"); KernelLog.Ln;
	ELSE
		WM.format := Raster.BGR565;
		KernelLog.String("WindowManager: 16-bit color"); KernelLog.Ln;
	END;
	NEW (session);  NEW(toucher);

	NEW(view, disp(Displays.Display));
	session.lock.AcquireWrite; session.AddView(view); session.lock.ReleaseWrite;
	FillSession(session, color, noPointer);

	IF (view.width0 > 0) & (view.height0 > 0) THEN
		r := Rect.MakeRect(0, 0, view.width0, view.height0);
	ELSE
		r := Rect.MakeRect(0, 0, 1600, 1200);
	END;
	session.AddDirty(r);
	WM.registry.Add(session, res);
	NEW(defaultMouse, 5, 15); defaultMouse.view := view;
	NEW(defaultKeyboard); defaultKeyboard.view := view;
END Replace;

PROCEDURE InitCharMaps;
VAR i: LONGINT;
BEGIN
	FOR i := 0 TO 127 DO CharToUnicode[i] := i END;
	CharToUnicode[128] := 0C4H;
	CharToUnicode[129] := 0D6H;
	CharToUnicode[130] := 0DCH;
	CharToUnicode[131] := 0E4H;
	CharToUnicode[132] := 0F6H;
	CharToUnicode[133] := 0FCH;
	CharToUnicode[134] := 0E2H;
	CharToUnicode[135] := 0EAH;
	CharToUnicode[136] := 0EEH;
	CharToUnicode[137] := 0F4H;
	CharToUnicode[138] := 0FBH;
	CharToUnicode[139] := 0E0H;
	CharToUnicode[140] := 0E8H;
	CharToUnicode[141] := 0ECH;
	CharToUnicode[142] := 0F2H;
	CharToUnicode[143] := 0F9H;
	CharToUnicode[144] := 0E9H;
	CharToUnicode[145] := 0EBH;
	CharToUnicode[146] := 0EFH;
	CharToUnicode[147] := 0E7H;
	CharToUnicode[148] := 0E1H;
	CharToUnicode[149] := 0F1H;
	CharToUnicode[150] := 0DFH;
	CharToUnicode[151] := 0A3H;
	CharToUnicode[152] := 0B6H;
	CharToUnicode[153] := 0C7H;
	CharToUnicode[154] := 2030H;
	CharToUnicode[155] := 2013H;
	FOR i := 156 TO 255 DO CharToUnicode[i] := i END
END InitCharMaps;

PROCEDURE CleanUp;
BEGIN
	IF session # NIL THEN
		IF toucher # NIL THEN toucher.alive := FALSE; toucher.timer.Wakeup END;
		session.ShutDown;
	 END
END CleanUp;

PROCEDURE Install*(context: Commands.Context);
VAR options: Options.Options; color: LONGINT; noPointer: BOOLEAN;
CONST DefaultColor = LONGINT(8080FFFFH);
BEGIN
	NEW(options);
	options.Add("c","bgColor",Options.Integer);
	options.Add("n","noMouseCursor",Options.Flag);
	IF options.Parse(context.arg, context.error) THEN
		IF ~options.GetInteger("bgColor", color) THEN color := DefaultColor END;
		noPointer := options.GetFlag("noMouseCursor");
	ELSE noPointer := FALSE; color := DefaultColor
	END;
	Replace(color, noPointer);

END Install;

PROCEDURE TraceChain*;
BEGIN
	session.CheckChain(TRUE);
END TraceChain;

PROCEDURE SetDoubleClick*(context: Commands.Context);
VAR options: Options.Options; speed: LONGINT;
BEGIN
	NEW(options);
	options.Add("s","speed",Options.Integer);
	IF options.Parse(context.arg, context.error) THEN
		IF options.GetInteger("speed", speed) THEN
			DoubleClick := speed
		END;
	END;
END SetDoubleClick;

BEGIN
	WMFontManager.Install;
	InitCharMaps;
	Modules.InstallTermHandler(CleanUp);
	DoubleClick := 500;
END WindowManager.