Dear Maintainer,

   * What led up to the situation?
      - Upgrading to Debian/Bullseye

   * What exactly did you do (or not do) that was effective (or
     ineffective)?
      1. Open the start menu
      2. Choose a sub-menu that has enough entries to fill the menu box. For example
         Applications/Internet
      3. Do NOT move your mouse. The list shows the first element selected, but the
         mouse pointer is further down on the list, where the submenu Internet was located
      4. Carefully click the mouse, avoiding any movement

   * What was the outcome of this action?
      - The first program in the menu gets started

   * What outcome did you expect instead?
      - The program under the mouse cursor should start

I did report this directly to KDE,
https://bugs.kde.org/show_bug.cgi?id=439674
but they closed it as RESOVED/FIXED, with a comment
   > This is not relevant any more in the new Kickoff. It's a pity that
   > Debian will not ship that for two more years.

This is not a serious issue for me, now that I have understood why the wrong program
starts occasionally. Was a bit confusing in the beginning.

Hi Heikki,

as you pointed out, this is resolved in the new Kickoff menu. If there
were a patch, we could apply it and resolve the issue.
But it seems the only solution is to use the new Kickoff menu. Then I'm
afraid we won't be able to fix it for the Plasma version in Bullseye.

However, as soon as Bullseye is released, we plan to push the newest
Plasma version from experimental to unstable and then it will be
available in testing soon after, if you want to install it from there.

If you have nothing further to add, I'll close the bug.

Fine, go ahead and close it. This was more or less the best I could expect.
I can live with it for now, and will try to upgrade to the latest, when it
reaches the (next) testing.