We ran into a problem here with the use of XkbKeycodeToKeysym which is reported in "[ tktoolkit-Bugs-3607830 ] XkbKeycodeToKeysym fails sometimes". I've fixed the problem with the patch attached to that bug report. However, there is another question about the use of Xkb: should there be an option to disable Xkb even if the server supports it? It seems that other applications sport this kind of option, and the Xkb API includes a call to disable the use of the extension. This leads me to believe this is a necessary choice that an application user may need to make in some cases.