Whenever iceweasel exits, whether it be via File->Quit, ^Q, etc. it does not return control to the icewm window we are now left looking at. Instead all the character input we do is not thrown away. Until the point we use ALT-TAB or the mouse to switch to a window. So even though we might be staring at the window we want to type characters into, we must do ALT-TAB and then another ALT-TAB, or else it is just like typing into a glass wall, our characters are thrown away. This does not happen with midori, nor with other packages running on icewm.