Note that if you just run off and loop on a job, then the GUI will be frozen and windows will mark it "not responding". Be sure to sprinkle in some DoOneEvent() or equivalent calls so your GUI keeps rolling while you work.

Also note that just because a button is disabled, doesn't mean it can't be click()ed again if the user is quick and/or tricky. (Eg: Win32-GuiTest) The enable state of the button itself makes a decent flag if the application isn't multithreaded.