Add check for open messageBoxes to prevent exit (PR #12984)
Relates to #12976
Summary:
NVDA was crashing when trying to exit NVDA while a messageBox was open (eg the About Dialog).
This is due to wx Idle Events firing on the dialogs while they are being forced to close in the exit process.
Repro steps:
- have NVDA running:
- Press NVDA+n then h to open the help menu, down arrow to "About dialog" and enter to open that.
- Press NVDA+Q then ENTER to quit NVDA
The change:
Prevent user initiated exit while a MessageBox dialog is open. If a modal is used, generally the outcome of the MessageBox is important and must be resolved before exit.
Co-authored-by: Reef Turner <reef@nvaccess.org>
