Brief summary of issue / Description of requested feature:

Connection window should only spawn once

Steps to reproduce the issue:

1. Start Mudlet. Move away or close the Connection window
2. Click the "connect" button repeatedly or press Alt+C in Mudlet main window
3. Multiple connection windows are spawned

Expected result of feature

3. Connection window is opened once. After that, not opened anymore again.

Extra information, such as Mudlet version, operating system and ideas for how to solve / implement:

Mudlet 3.21 on Win10

Example: