Bug present for some time. Still valid for weston master. Any xwayland app going fullscreen doesn't get into fullscreen mode correctly: it's not at position (0,0), and the shell bar at the top is above the app. It's due to the shell set_fullscreen function, which doesn't actually apply fullscreen right away. some xdg_sell patches introduced this behaviour. For Xwayland, that means that fullscreen mode is never actually applied for the application.
commit 47792415165888676078eb3eb98ac4b97ba34140 Author: Kristian Høgsberg <krh@bitplanet.net> Date: Sun May 4 13:47:06 2014 -0700 xwayland: Fix fullscreen mode With xdg_shell wl_shell starting to diverge in how they work, there's less shared code in set_fullscreen(). The problem is that the xwayland window manager calls into set_fulscreen() which now doesn't complete the fullscreen transition. Add shell_interface_set_fullscreen() for the shell interface set_fullscreen hook to use. https://bugs.freedesktop.org/show_bug.cgi?id=78230
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