Properly dispose resources allocated by Bitmap. (#877)

Author: claudiamurialdo

dotnet/src/dotnetframework/GxClasses/Core/GXUtilsCommon.cs

@@ -5959,9 +5959,12 @@ public static string RoundBorders(string imageFile, int topLeftRadius, int topRi
 
 									g.FillPath(Brushes.White, path);
 
-									using (TextureBrush br = new TextureBrush(new Bitmap(OriginalImage), WrapMode.Clamp))
+									using (Bitmap bitmap = new Bitmap(OriginalImage))
 									{
-										g.FillPath(br, path);
+										using (TextureBrush br = new TextureBrush(bitmap, WrapMode.Clamp))
+										{
+											g.FillPath(br, path);
+										}
 									}
 								}
 							}