I've now added an incomplete workaround for the text rendering bug in QtQuick2 (see commit). You can use the element TextWA instead of Text in QtQuick2 (it only provides properties text, font.*, and color but that's enough to work as a label). If nobody finds a real solution we may export this element as "Text" some day (with additional properties). TextWA uses a painter to render the text and so avoids the (most likely) OpenGL ES related bug.

I've also uploaded a libx11 source package to extras-devel which properly exports xcb (you need libx11-with-xcb-6 and libx11-xcb1). Be careful with this packages as libx11-with-xcb-6 replaces "/usr/lib/libX11.so.6.2.0". Don't reboot after the installation unless you checked that several different programs work and make sure you can enable ssh without the keyboard after reboot, if something went wrong (or use backupmenu etc.). "apt-get upgrade" will not trigger the installation in any case, as the names are different and "provides" are used.