On strange loop example, if you try to move around slides and there's a highlighted text (in this case it's a red text), then you can see a few glitches under the box that contains the text. One thing to note about it is that these texts have some effects when you put cursor on it. I can see this bug in a similar way on Qt and Nix, and more clearly on EFL.
Some investigation to figure out if this was a regression (tested on qt):
r147009 - displayed with artifacts
r143738 - displayed with artifacts
r138818 - not even displaying
r138735 - not even displaying
r138476 - displayed with artifacts
Looks like we've been like this forever, but at some point we've made it to stop working at all.
the latest WinCairo also reproduce the issues.
Filed another bug: Bug 241699 – TextureMapperGL: rendering glitch of a 3d transformed text in Strange-Loop-2012