Use the Bool type from X11/Xdefs.h for winShowWindowOnTaskbar().
This is the boolean type we should be using inside the X server, rather than
BOOL, which evaluates to either the Win32 API type, or the Xlib API type,
depending on the context...
Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>