Peculiar behavior trying to set active menu item

[Charles]

If you look at
https://codebrowser.dev/qt6/qtbase/src/widgets/widgets/qmenu.cpp.html#_ZN5QMenu10timerEventEP11QTimerEvent,
QMenu has a timerEvent. This resets the highlight.

What you can do is store the active item in an attribute and reselect it
after the timerEvent

def timerEvent(self, event):
        super().timerEvent(event)
        if self._active_action:
            self.setActiveAction(self._active_action)


On Thu, Mar 6, 2025 at 4:03 AM John Sturtz <john at sturtz.org> wrote:

> 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
>
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