Segfault when dragging mouse in half-empty panel

[egmont]

Go to a directory with fewer files than fit in the panel, i.e. with some empty space under the listing.

Click on one of the files and keep the mouse button held down.

Slowly move the mouse downwards.

As it leaves the last file, the last file becomes unhighlighted. This is already unexpected because the current file cursor now points to nowhere.

Keep slowly moving the mouse down to the very bottom (the bottom button bar, or even outside of the terminal window) and then back to the panel. Repeat a few times if necessary (while still holding down the mouse button) => segfault.

Broke in 1ac839d20c2a277d54aa00286b69f61ffeaec929. Prior to that, as expected, the current file cursor would remain on the last file of the panel, and I could not trigger a segfault.

[egmont]

bt full