dragging a window under gnome using the left mouse button [i
have gnome/enlightenment] causes any programs with an X
interface to freeze  and not update their display until I
released the mouse button.

Notable with xmms , top running in xterm .....

xmms music stops , graphic display stops.

I'm afraid I don't have time to look more closely into this
and provide you with more info. It may even be a bug in X.

could be a problem if someone has a realtime app running
under X which then proceeds to die nastily , just because
the person is drag selecting.

email me if you want more info on my setup.