This was returning a background positioning area relative to the viewport, but we don't fix the display item when it doesn't have an image. DLBI was then attempting to shift the positioning area to compensate for scroll changes, and we detecting that the background moved. A nicer fix would be to split nsDisplayCanvasBackground into separate color/image items, and then not even create the image items if they are empty.
Attachment #690264 - Flags: review?(roc)
Attachment #690264 - Attachment is patch: true
Attachment #690264 - Flags: review?(roc) → review+
It should be pretty easy to use paint_listener.js to write a testcase for this. Please do.
Status: NEW → RESOLVED
Closed: 7 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla20
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