Same is true if focus of the mouse is in player

Thanks for reporting,
tracking as https://www.ventismedia.com/mantis/view.php?id=18628

I am applying MM 5.0.2.2524 portable
Skin Material Design

I have defined a hotkey "Shift+C" to: collapse tree.

If the focus of the mouse is in the second line from the top (e.g., minimize left panel, Previous View ...) the tree collapses as desired, but at the same time an input window for the search opens.

On the other hand if the focus of the mouse in the Main panel, the tree collapses without opening a search window.