User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0 Build ID: 20161114144856 Steps to reproduce: Set layers.enable-tiles to true. Open slack for example. Actual results: Rendering artifacts with square shapes in wrong (solid) color.
This happens with and without OpenGL composited layers. With both Cairo and Skia content rendering.
This was working with Firefox 49. (The reason I enabled layers.enable-tiles was that I get rendering artifacts with GL composited rendering at 4K resolution without tiles.)
Created attachment 8813084 [details] screenshot.png https://slack.com/ seems to be a good demo for the issue also.
User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/53.0 I have tested your issue on latest Firefox release v50.0, latest Nightly build (Buid ID; 20161124030208) and managed to reproduce it. I have followed the steps from comment 0 and used the website from comment 4.