Fixes #4924. Setting Shortcut.Key to Key.Empty now removes the key binding

[tig]

Fixes #4924

Problem

Shortcut.UpdateKeyBindings had an early-return guard:

if (!Key.IsValid)
{
    return;
}

Key.IsValid is false for Key.Empty, so setting shortcut.Key = Key.Empty was a no-op — the previously-registered binding was never removed. The old key kept firing the action.

Fix

• Remove the if (!Key.IsValid) return guard entirely.
• Guard only the add path with if (Key != Key.Empty), so:
  • The old binding is always removed.
  • Key.Empty is never registered as a new binding.

Changes

File	Change
Terminal.Gui/Views/Shortcut.cs	Remove invalid early-return; add Key.Empty guards on add paths
Tests/…/ShortcutTests.KeyDown.cs	Two new failing-before/passing-after unit tests
Examples/UICatalog/Scenarios/Keys.cs	Add "Disable Quit Key" shortcut to demo the fix; use StatusBar with Dim.Fill(statusBar) for list views
Terminal.Gui/Drivers/AnsiDriver/AnsiInput.cs	Expose KeyboardFlags as a public property
Terminal.Gui/Drivers/AnsiDriver/AnsiComponentFactory.cs	Include kitty keyboard state in driver name
Terminal.Gui/Drivers/DriverImpl.cs	Make KittyKeyboardProtocol public
Terminal.Gui/Drivers/IDriver.cs	TODO comment for capabilities extension
Tests/…/InitTests.cs	Update assertion for new driver name format
Tests/…/AllDriverTests.cs	Update assertion for new driver name format

Tests

Two new tests in ShortcutTests.KeyDown.cs:

• Setting_Key_To_Empty_Removes_KeyBinding — view-scoped binding
• Setting_Key_To_Empty_Removes_AppLevel_KeyBinding — app-scoped (BindKeyToApplication = true)

Both fail on the unfixed code and pass with the fix.

[Copilot]

Pull request overview

Fixes #4924 by ensuring that setting Shortcut.Key = Key.Empty actually removes any previously-registered key binding rather than leaving the old binding active.

Changes:

• Updated Shortcut.UpdateKeyBindings to always remove the old binding and to skip adding a new binding when Key is Key.Empty.
• Added unit tests covering both view-scoped and application-scoped bindings being removed when Key is set to Key.Empty.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
Terminal.Gui/Views/Shortcut.cs	Adjusts key-binding update logic to allow unbinding via Key.Empty.
Tests/UnitTestsParallelizable/Views/ShortcutTests.KeyDown.cs	Adds regression tests for unbinding behavior; minor cleanup to event handlers/loops.

[BDisp]

Great. Now assigning a command to a key is always guaranteed, as long as the key is not empty.