Step 1: Start Qt Designer. Open your form. Qt designer hangs. Kill that stuff.
Step 2: Restart, but open another form. Qt Designer works just fine.
Question your sanity and repeat step 1 to see whether the hanging was just a glitch in the Matrix. Be stumped to see that it hangs again.
(Possible extension: create your favorite permutational combination of step 1 & 2 and repeat into infinity 😉 )
If this scenario seems familiar to you, then certainly read on…
Remember my little QtWorkbench issue I blogged about? Well, it seemed, the story got a tail too (that’s why I had to blog that first before I could say this =)).
During my struggle for correct compilation, I had modified the windowModality flag of my QMainWindow to Qt::Modal, in a desperate attempt to guide my app into the “Right Thread”. 😉
If I had modified that flag at any other point, I would have noticed the problem immediately, but being preoccupied with my QFtp thread problem at that time, I never went back to Designer and didn’t notice..
I know, it’s a stupid of me, but I still think it’s kind of a bug in Qt Designer. If you shouldn’t change the window modality of a main window, then they shouldn’t let you. 🙂 Moreover, you can’t change it back since as soon as you open your form, the form gets simulated in real-time and the dead-lock occurs. Or maybe even eventloop hijacking, sounds more l33t. 😛
Luckily, the gui is stored in plain XML, so you can just delete that section and you’re all set.