try this make a new GUI from the template, save it then go into the debugger and set a break point in the button callback procedure and you should see an error message saying
Error code 4
Equals Sign Expected
line 35
CASE %WM_COMMAND
It also seems to open the debug window with random settings.
Debugging UI application is quite complex due to the many messages are fired to the callback functions even if debugger is in "waiting for user input" mode.
In any case it dosn't have to generate errors. I will check asap.