Selection kept when tool is closed by hotkey

[guillaumecardon]

To reproduce the bug :

• Open Scenery Manager
• Click on "Select"
• Select an area
• Click on "Copy" (or Cut)
• Close the tool with the game hotkey (backspace key by default)
• Tool is closed, but selection is always present.

To remove the selection, you need to re-open Scenery Manager, click on "Select".

(Obviously, option "Keep selection when finished" is unchecked )