class TrackCanvas;
-#define HANDLE_W 8
-#define HANDLE_H 8
+#define HANDLE_W xS(8)
+#define HANDLE_H yS(8)
+
+// draw mode:
+// NO_DRAW used in MWindowGUI/TimelinePane update to disable canvas update
+// NORMAL_DRAW causes incremental drawing of pixmaps. Used for navigation and index refresh.
+// FORCE_REDRAW causes all resource pixmaps to be redrawn from scratch. Used by editing.
+// IGNORE_THREAD causes resource pixmaps to ignore picon thread. Used by Piconthread.
+#define NO_DRAW 0
+#define NORMAL_DRAW 1
+#define FORCE_REDRAW 2
+#define IGNORE_THREAD 3
#endif