In the given example the raster images on top of the SVG file (above the big image) partially appear/disappear, but they should always be visible. Thank you for having a look at the example!
Interesting. I also see this on the console: (event handler):Can't find variable: mousemove (event handler):Can't find variable: mousemove
Created attachment 13781 [details] Initial patch This fixes 12126, 12572 and this bug. Thanks for the report & pointing me to it Andreas!
Created attachment 13796 [details] Updated patch Include a LayoutTest.
Comment on attachment 13796 [details] Updated patch looks good
Landed in r20469.