Notepad++ search result window does not respond on keyboard commands

As you might know, the keyboard shortcut ALT+SPACE opens a popup menu, which you can use to move, minimise or maximise the window you're working with.

Using this popup menu on Notepad++ in general is working fine (although I believe this is Windows technology, not notepad++ specific), as you can see here:

Appearance of the popup menu after hitting ALT+SPACE:

The effect on Notepad++ (the appearance of the "Movement mouse cursor" in the heading of the Notepad++ window):

This allows me to move Notepad++ window around, using the keyboard (left, right, up and down arrows).

When I try this with the search result window inside Notepad++, this doesn't work (it only reacts on mouse events, not on the keyboard).

I'm currently working on Notepad++ version v8.5.7, but the same behaviour is also seen on version v8.5.4.

Is this a known Notepad++ bug and are there any plans to get this solved?

Thanks in advance