Visual indicator for keyboard shortcut passthrough mode in RDP sessions

Description:
Add a visual border around RDP sessions when keyboard shortcuts are configured to pass through to the remote machine rather than execute locally.

Problem: Currently, there's no visual feedback showing whether keyboard shortcuts (Alt+Tab, Windows key, etc.) will be captured by the local machine or passed through to the remote session. This creates confusion - I'll try to Alt+Tab expecting to switch windows locally, but the shortcut gets sent to the remote machine instead, or vice versa. Since RDM sessions can be configured differently for passthrough behavior, I constantly have to remember which sessions are configured which way.

Requested Solution: Display a distinct colored border (configurable) around the RDP window when keyboard shortcuts are set to pass through to the remote session. The border should be visible but not obtrusive - something like a 2-3 pixel colored outline. When passthrough is disabled and shortcuts execute locally, no border appears (or use a different color).

Benefit: Instant visual confirmation of which keyboard mode I'm in before I press shortcuts. Eliminates the guess-work and frustration of shortcuts going to the wrong machine.