If I close preferences with OK or Cancel, things seem fine, but if I click on the Geany main window while the prefs dialog is open, then the dialog disappears and Geany becomes completely unresponsive. I have to kill it using Windows Task Manager.
OK, now I feel really stupid. I can actually get the prefs dialog back if I move or minimize the Geany main window. It's kind of unexpected behavior because it's partially modal (blocking most operations of Geany's main window) but partially not (allowing itself to not be in front).
Maybe this is unexpected to me because I have become too used to Windows, which probably has different conventions than most *nix or GTK apps. Sorry for not figuring this out before I sent my previous post.
John