Menu Bar - Strange keyboard navigation used

### Bug description

`Menu Bar` does not follow standard navigational functionality when using keyboard ARROW keys

### Steps to reproduce

1. Click on `Menu Bar` category to open drop down
2. Now try common navigation using your UP DOWN LEFT RIGHT ARROW keys

### Expected behavior

To use ALT+letter or click on `Menu Bar` categories with mouse it opens drop downs.
Then be able to experience standard navigational behavior when using ARROW keys

LEFT ARROW / RIGHT ARROW = would open the drop down for the category to the left/right
LEFT ARROW / RIGHT ARROW FLYOUTS = would open / close flyout
UP ARROW / DOWN ARROW = navigate up/down

### Actual behavior

LEFT ARROW = closes the drop down
RIGHT ARROW = navigates highlight cursor down (strange)
RIGHT ARROW ON FLYOUT = opens flyout

If LEFT ARROW is used to close the drop down, you then seen white rectangle (if using dark theme) around the categories name.
This then allows LEFT / RIGHT ARROWS to go left / right to other category names but does not open the drop down

### Audacity Version

Audacity 4 Alpha2 - Official AppImage

### Operating system

Linux

### Additional context

Hopefully this functionality is a bug in Audacity that can be fixed and not a decision made by QT that cannot be.

RELATED POST
Another standard behavior that is missing is to be able to close drop downs using ESCAPE key which I made a post about here if anyone is interested
https://github.com/audacity/audacity/issues/10003