Using ThinBasic 1.8.9.0, create a new program and select the GUI "CustomDialogWithButton" template. Run it normally with no modifications, it works fine. However, start the debugger (F8) and run it (F5). You get a syntax error on line 35 (it doesn't like the SELECT CASE statement) and when you click OK, the debugger crashes. This happens on both Windows 7 and Windows XP, so it doesn't look like a problem that's platform specific.