User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100823 Minefield/4.0b5pre ID:20100823055515 Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100823 Minefield/4.0b5pre ID:20100823055515 Silverlight become black when popup is hidden. Contents area is repainted when window blur and focus. Reproducible: Always Steps to Reproduce: 1. Start Minefield with new profile 2. Open URL ( http://www.perpetuumsoft.com/Demo/slviewer/default.aspx ) 3. Reload ( due to Bug 585437 ) 4. Click star icon and hide popup or Click App button and hide popup. Actual Results: Contemts area become black. Expected Results: Should not. Regression window: Works: http://hg.mozilla.org/mozilla-central/rev/4192ba38ebee Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100819 Minefield/4.0b5pre ID:20100820130619 Fails: http://hg.mozilla.org/mozilla-central/rev/95a39e236cc4 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100820 Minefield/4.0b5pre ID:20100820131417 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=4192ba38ebee&tochange=95a39e236cc4 Candidate bug: Bug 582057 - Replace platforms widgets in content processes with cross-platform fake widgets

This seems to WFM with the fix in bug 589864, but I'm not sure I was doing step 4 correctly. Please reopen if you can repro with tomorrow's nightly.