I have this problem periodically (exaserbated when I try to drag a
class from a normal browser to StarBrowser).  I've found that the
world often has some bogus steppers in it and that:
Utilities cleanseOtherworldlySteppers (or maybe
cleanseOtherWorldlySteppers?)
fixes it.  Thanks to the folks on IRC for pointing out this fix, BTW.
David Shaffer
ar writes:
 > I'm having a problem with my 3.6g linux image where button clicks
 > eg to close a window, or to open a debugger from the walkback
 > window, are not processed until I move the mouse.
 >
 > This only happens in one of my images. I dont know of anything that
 > happened in this image that could account for this particular
 > trauma. I dont go near the UI code and I never save the image with
 > state changes in it ( on startup, I replay my recent changes from
 > previous session, then save)
 >
 > As far as packages the the only "interesting" one loaded that I can
 > think of is worlds of squeak removal(2).
 >
 > Anyone come across this problem?