Peculiar behavior trying to set active menu item

[John Sturtz]

This probably qualifies as one of those things it occurred to me I 
should be able to do.  So then, of course, I set out to try it.  And it 
doesn't seem to work quite as I expect.  (Perhaps the best answer is 
"Don't do that"?)

I've got a QToolButton object with a menu attached to it.  My idea is to 
implement menu shortcut keys.  So if you hit an alphabetic key, it makes 
active the first item in the menu that starts with that letter.  If you 
hit the same key again, it takes you to the next matching item.  And so 
on.  (And if you get to the last, it wraps around and re-selects the 
first again).

To that end, I create a custom Menu class derived from QMenu.  The 
button's main menu is an object of the Menu class.  Also, one item in 
the main menu has a submenu, which is also an instance of Menu.  I 
re-implement the Menu class .keyPressEvent() method, and when matching 
letters are hit, set the active menu item with .setActiveAction().

Everything seems to work fine until I display the submenu.  Then things 
turn flaky.

I have a small reproducible example attached.  'Flaky' behavior can be 
observed (at least, on my machine) as follows:

Click the button, and a menu of some cities displays.  Hit 'A', 'B', 
'H', or 'L' to select cities starting with those letters (the 
non-submenu items), and all works as expected.

Now hit 'D' to select Denver.  It makes that item active and displays 
the submenu.  Hit the left arrow to make the submenu disappear.  Then 
hit 'A' to select Anchorage.  It highlights ... for about a second.  And 
then the selection background disappears.

Any ideas why this would be?  My first thought was that Qt maintains 
some state information regarding which menu item is active, and the main 
menu and submenu are interfering with each other.  It is true that the 
are the same class.  But they are separate instances of that class, so 
I'd have expected they'd be able to function independently of one 
another.

Any thoughts appreciated.

Thanks!

/John
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.riverbankcomputing.com/pipermail/pyqt/attachments/20250305/bbd5147c/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: post.py
Type: text/x-python
Size: 3432 bytes
Desc: not available
URL: <https://www.riverbankcomputing.com/pipermail/pyqt/attachments/20250305/bbd5147c/attachment.py>