Create a 2D window and then manually focus a different window on your desktop, call SDL_PumpEvents() so the X11 driver sets its this->hidden->switch_waiting, then set a fullscreen OpenGL window (which makes the X11 driver tear down and create a new window instead of just resizing the existing one), poll for events, and the newly-created window will think it needs to pop back to a window. Fixed by resetting switch_waiting to zero if X11_CreateWindow() had to tear down a previous window.

Makefile.in
Makefile
configure
config.cache
config.log
config.status
autom4te*
aclocal.m4
checkkeys
graywin
loopwave
testalpha
testbitmap
testcdrom
testcpuinfo
testerror
testgamma
testgl
testhread
testjoystick
testkeys
testlock
testoverlay
testoverlay2
testpalette
testsem
testsprite
testtimer
testtypes
testver
testvidinfo
testwin
testwm
threadwin