Some window managers (e.g. kwin_x11) clear _NET_WM_STATE when a window
is unmapped/withdrawn. This caused layer shell windows to lose states like
_NET_WM_STATE_ABOVE, _NET_WM_STATE_SKIP_TASKBAR, etc. when hidden and
re-shown via toggle. The result was inconsistent behaviour between the
first show and subsequent shows.
Fix by calling update_wm_hints() before XMapWindow in
_glfwPlatformShowWindow() for layer shell windows, which re-applies all
WM state properties (_NET_WM_STATE, window type, strut, size hints)
before each map operation.
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