Improve hotkey capture and validation

MainWindow.xaml.cs

@@ -312,13 +312,78 @@ public partial class MainWindow : Window
             return;
         }
 
-        controller.Config.Hotkey = string.IsNullOrWhiteSpace(HotkeyBox.Text) ? "Ctrl+Alt+Space" : HotkeyBox.Text.Trim();
+        controller.Config.Hotkey = string.IsNullOrWhiteSpace(HotkeyBox.Text)
+            ? "Ctrl+Alt+Space"
+            : HotkeyService.Normalize(HotkeyBox.Text.Trim());
         controller.Config.DisplayMode = DisplayModeBox.SelectedItem is LauncherDisplayMode mode
             ? mode
             : LauncherDisplayMode.LargeIconWithText;
         ApplyCurrentItem();
     }
 
+    private void HotkeyBox_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
+    {
+        Key key = e.Key == Key.System ? e.SystemKey : e.Key;
+        if (key == Key.ImeProcessed)
+        {
+            key = e.ImeProcessedKey;
+        }
+
+        if (key is Key.LeftCtrl or Key.RightCtrl or Key.LeftAlt or Key.RightAlt or Key.LeftShift or Key.RightShift
+            or Key.LWin or Key.RWin)
+        {
+            e.Handled = true;
+            return;
+        }
+
+        if (key is Key.Back or Key.Delete or Key.Escape)
+        {
+            HotkeyBox.Text = "";
+            e.Handled = true;
+            return;
+        }
+
+        ModifierKeys modifiers = Keyboard.Modifiers;
+        if (modifiers == ModifierKeys.None)
+        {
+            StatusText.Text = "Press a hotkey with Ctrl, Alt, Shift, or Win plus another key.";
+            e.Handled = true;
+            return;
+        }
+
+        HotkeyBox.Text = FormatHotkey(modifiers, key);
+        HotkeyBox.CaretIndex = HotkeyBox.Text.Length;
+        StatusText.Text = "Click Save to apply the new hotkey.";
+        e.Handled = true;
+    }
+
+    private static string FormatHotkey(ModifierKeys modifiers, Key key)
+    {
+        List<string> parts = [];
+        if (modifiers.HasFlag(ModifierKeys.Control))
+        {
+            parts.Add("Ctrl");
+        }
+
+        if (modifiers.HasFlag(ModifierKeys.Alt))
+        {
+            parts.Add("Alt");
+        }
+
+        if (modifiers.HasFlag(ModifierKeys.Shift))
+        {
+            parts.Add("Shift");
+        }
+
+        if (modifiers.HasFlag(ModifierKeys.Windows))
+        {
+            parts.Add("Win");
+        }
+
+        parts.Add(key.ToString());
+        return string.Join("+", parts);
+    }
+
     private void LoadStartupState()
     {
         isLoadingStartupState = true;
@@ -569,9 +634,24 @@ public partial class MainWindow : Window
             return;
         }
 
-        ApplyConfigFields();
-        ConfigService.Save(controller.Config);
-        controller.ReloadConfig();
+        string previousHotkey = controller.Config.Hotkey;
+        try
+        {
+            ApplyConfigFields();
+            ConfigService.Save(controller.Config);
+            controller.ReloadConfig();
+        }
+        catch (Exception ex) when (ex is FormatException or InvalidOperationException)
+        {
+            controller.Config.Hotkey = previousHotkey;
+            ConfigService.Save(controller.Config);
+            controller.ReloadConfig();
+            HotkeyBox.Text = previousHotkey;
+            MessageBox.Show($"Could not apply hotkey.\n\n{ex.Message}", "Taskbar Launcher");
+            StatusText.Text = $"Hotkey was not changed. Current hotkey: {previousHotkey}";
+            return;
+        }
+
         LauncherItem? reloadedSelection = selectedPath is null ? null : FindItemByPath(controller.Config.Items, selectedPath);
         RefreshView(reloadedSelection);
         StatusText.Text = reloadedSelection is null