Fix wx assertion error (PR #12363)
Fixes: #12336
Fixes: #12220
# Summary of the issue:
Issue#12220 Causes a wx assertion message when either the Braille or Speech settings panels are open.
This seems to be related to the expando text control used on both panels.
The assertion is in wx's accessibility code, which has been introduced in our latest upgrade of wxPython.
The PR #12292 attempted to fix this by explicitly destroying the expando text control when closing.
In #12292 it was missed that the onSave callback was also called for the apply button.
# Description of how this pull request fixes the issue:
While looking at adding an explicit close callback for panels, I noticed that Destroy was being called manually during the event handler.
Scheduling a destroy call after the event handler seems to resolve this issue.
As I understand, destroying children explicitly is not required.
While here also:
- Tidy onSave / onApply
- Add type info for 'catIdToInstanceMap' and 'categoryClasses'
