diff --git a/ChangeLog b/ChangeLog
index 4011eb880..b8f8463ff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2002-08-23 02:39  Alexander Malmberg  <alexander@malmberg.org>
+
+        * Source/NSImage.m (-lockFocusOnRepresentation:): Use a
+        compositerect to clear the alpha channel if the background color
+        isn't opaque.
+
 2002-08-16  Adam Fedor  <fedor@gnu.org>
 
 	* Source/NSGraphicsContext.m: Define colorspace constants
diff --git a/Source/NSImage.m b/Source/NSImage.m
index b7b60dea0..1cfc48b11 100644
--- a/Source/NSImage.m
+++ b/Source/NSImage.m
@@ -899,6 +899,19 @@ repd_for_rep(NSArray *_reps, NSImageRep *rep)
 	{
 	  repd->bg = [_color copy];
 	  [_color set];
+	  
+	  if ([_color alphaComponent] < 1)
+	    {
+	      /* With a Quartz-like alpha model, alpha can't be cleared
+	         with a rectfill, so we need to clear the alpha channel
+		 explictly. (A compositerect with NSCompositeCopy would
+		 be more efficient, but it doesn't seem like it's 
+		 implemented correctly in all backends yet (as of 
+		 2002-08-23). Also, this will work with both the Quartz-
+		 and DPS-model.) */
+	      PScompositerect(0, 0, _size.width, _size.height,
+			      NSCompositeClear);
+	    }
 	  NSRectFill(NSMakeRect(0, 0, _size.width, _size.height));
 	}
     }