Add new Key support

- [ ] modifiers: left ontrol, right control, same for alt and shift
- [ ] TAB

This would allow to update visual display when a modifier key is pressed, but the mouse stay put. Currently there is no way to have the most current keyboard state in that case.

The issue requests distinct left/right Control, Alt, and Shift support plus TAB, so start by locating the keyboard event handling and existing key definitions. Verify how modifier-only events update the visual keyboard state while the mouse remains stationary. No files or tests are identified in the issue, so the relevant entry points and completion checks must first be established.

Written by the indexing model from the issue text.