make compilable

git-svn-id: https://svn.inf.ethz.ch/svn/lecturers/a2/trunk@8087 8c9fc860-2736-0410-a75d-ab315db34111

source/AGfx.Mod

@@ -74,7 +74,7 @@ MODULE Gfx; (** portable *)	(* eos  *)
 		ClipAreaDesc* = RECORD END;
 
 		(** graphics context **)
-		Context* = OBJECT
+		Context* = OBJECT { ABSTRACT }
 		VAR
 			mode*: SET;	(** current drawing mode **)
 			path*: GfxPaths.Path;	(** current path in device coordinates (updated only if mode contains the 'Record' flag) **)

source/AGfxRaster.Mod

@@ -52,7 +52,7 @@ MODULE GfxRaster; (** portable *)	(* eos  *)
 		END;
 
 		(** abstract raster context **)
-		Context* = OBJECT (Gfx.Context)
+		Context* = OBJECT { ABSTRACT } (Gfx.Context)
 		VAR
 			clipReg*: GfxRegions.Region;	(** region inside clip path **)
 			col*: Gfx.Color;	(** current color **)