When using non opaque background, some overlap lines appear due to filling some pixel lines twice. Before it did not matter as only opaque bg was allowed, and it even compacted the text a bit. The fix spreads a bit the lines to overcome the issue. As a plus no text should touch the top edge ever (slashes did, for example). Compare: http://www.infernal-iceberg.com/blender/stamp-alpha-overlap.png http://www.infernal-iceberg.com/blender/stamp-alpha-cleanup.png