I have a problem that affects both hhexen and hheretic. After about 10 minutes of play (I have not timed it precisely) my keyboard locks up. If I am in full-screen mode, I get kicked back into windowed mode. The hhexen (or hheretic) window remains focused, and continues running. Enemies usually run over and kill me pretty promptly. My mouse cursor is invisible, and I cannot defocus the game. I can still mouselook, but I cannot move or attack. No keyboard combinations will allow me to change window focus.
I can press CTRL+ALT+F1 to switch to a virtual terminal, run killall -9 hhexen-gl and then I switch back to X11 using CTRL+ALT+F7, and my mouse and keyboard are working again.
This happens no matter whether I play in full-screen or windowed mode.
I have tried compiling without OpenGL, and it makes no difference.
I am using the latest SVN trunk.
My OS is Ubuntu Linux 9.04
My hardware is a Lenovo Thinkpad X200
I have not noticed any other games with this problem. I have tested other sdl+opengl games.