Maybe it was just me, but I have been annoyed by how my mouse settings were being ignored by radiant. Whenever I alt+tab’ed to Radiant, the mouse speed was so slow.
I thought it was a problem with radiant. But I had also extended my list of suspects to OpenGL and even the windows version of GtK. Then while removing and installing a new mouse driver, I noticed that with the native mouse driver this problem didn’t exist. After I had installed the new mouse driver I found a french site with some reg keys, that I wanted to try. But before I got around to it I noticed, that in the Logitech driver, right below the slider where you set the speed, was a checkbox called something in the order of ‘disable this for games’. I unchecked that one and now Radiant is using my mouse speed setting. 
Anyway, I just wanted to share.