UI: Close window hotkeys (#15227)

Content.Client/UserInterface/Systems/CloseWindow/CloseAllWindowsUIController.cs

@@ -0,0 +1,34 @@
+using Content.Client.Gameplay;
+using Content.Client.Info;
+using Robust.Client.Input;
+using Robust.Client.UserInterface;
+using Robust.Client.UserInterface.Controllers;
+using Robust.Client.UserInterface.CustomControls;
+using Robust.Shared.Input;
+using Robust.Shared.Input.Binding;
+
+namespace Content.Client.UserInterface.Systems.Info;
+
+public sealed class CloseAllWindowsUIController : UIController
+{
+    [Dependency] private readonly IInputManager _inputManager = default!;
+    [Dependency] private readonly IUserInterfaceManager _uiManager = default!;
+
+    public override void Initialize()
+    {
+        _inputManager.SetInputCommand(EngineKeyFunctions.WindowCloseAll,
+            InputCmdHandler.FromDelegate(session => CloseAllWindows()));
+    }
+
+    private void CloseAllWindows()
+    {
+        foreach (var childControl in new List<Control>(_uiManager.WindowRoot.Children)) // Copy children list as it will be modified on Close()
+        {
+            if (childControl is BaseWindow)
+            {
+                ((BaseWindow) childControl).Close();
+            }
+        }
+    }
+}
+