Improve minimizing to tray, and restore the existing instance if SMXConfig is launched when it's already minimized to the tray.

smx-config/App.xaml.cs

@@ -2,6 +2,7 @@ using System;
 using System.Windows;
 using System.Runtime.InteropServices;
 using System.IO;
+using System.Threading;
 
 namespace smx_config
 {
@@ -24,6 +25,13 @@ namespace smx_config
         {
             base.OnStartup(e);
 
+            // If an instance is already running, foreground it and exit.
+            if(ForegroundExistingInstance())
+            {
+                Shutdown();
+                return;
+            }
+
             // If we're being launched on startup, but the LaunchOnStartup setting is false,
             // then the user turned off auto-launching but we're still being launched for some
             // reason (eg. a renamed launch shortcut that we couldn't find to remove).  As
@@ -82,13 +90,38 @@ namespace smx_config
                 window.Closed += MainWindowClosed;
                 window.Show();
             }
-            else if(window.WindowState == WindowState.Minimized)
+            else if(IsMinimizedToTray())
             {
-                window.WindowState = WindowState.Normal;
+                window.Visibility = Visibility.Visible;
                 window.Activate();
             }
             else
-                window.WindowState = WindowState.Minimized;
+            {
+                MinimizeToTray();
+            }
+        }
+
+        public bool IsMinimizedToTray()
+        {
+            return window.Visibility == Visibility.Collapsed;
+        }
+
+        public void MinimizeToTray()
+        {
+            // Just hide the window.  Don't actually set the window to minimized, since it
+            // won't do anything and it causes problems when restoring the window.
+            window.Visibility = Visibility.Collapsed;
+        }
+
+        public void BringToForeground()
+        {
+            // Restore or create the window.  Don't minimize if we're already restored.
+            if(window == null || IsMinimizedToTray())
+                ToggleMainWindow();
+
+            // Focus the window.
+            window.WindowState = WindowState.Normal;
+            window.Activate();
         }
 
         private void MainWindowClosed(object sender, EventArgs e)
@@ -123,6 +156,33 @@ namespace smx_config
             }
         }
 
+        // If another instance other than this one is running, send it WM_USER to tell it to
+        // foreground itself.  Return true if another instance was found.
+        private bool ForegroundExistingInstance()
+        {
+            bool createdNew = false;
+            EventWaitHandle SMXConfigEvent = new EventWaitHandle(false, EventResetMode.AutoReset, "SMXConfigEvent", out createdNew);
+            if(!createdNew)
+            {
+                // Signal the event to foreground the existing instance.
+                SMXConfigEvent.Set();
+                return true;
+            }
+
+            ThreadPool.RegisterWaitForSingleObject(SMXConfigEvent, ForegroundApplicationCallback, this, Timeout.Infinite, false);
+
+            return false;
+        }
+
+        private static void ForegroundApplicationCallback(Object self, Boolean timedOut)
+        {
+            // This is called when another instance sends us a message over SMXConfigEvent.
+            Application.Current.Dispatcher.Invoke(new Action(() => {
+                App application = (App) Application.Current;
+                application.BringToForeground();
+            }));
+        }
+
         // Create a tray icon.  For some reason there's no WPF interface for this,
         // so we have to use Forms.
         void CreateTrayIcon()

smx-config/Helpers.cs

@@ -357,6 +357,9 @@ namespace smx_config
             shortcut.WindowStyle = 0;
             shortcut.Save();
         }
+
+        [DllImport("user32.dll", CharSet = CharSet.Auto)]
+        public static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
     }
 
     // This class just makes it easier to assemble binary command packets.

smx-config/MainWindow.xaml.cs

@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Media;
+using System.Windows.Interop;
 
 namespace smx_config
 {
@@ -65,20 +66,16 @@ namespace smx_config
                 if(result == MessageBoxResult.No)
                     e.Cancel = true;
             };
-
-            StateChanged += delegate(object sender, EventArgs e)
-            {
-                // Closing the main window entirely when minimized to the tray would be
-                // nice, but with WPF we don't really save memory by doing that, so
-                // just hide the window.
-                ShowInTaskbar = WindowState != WindowState.Minimized;
-            };
         }
 
         public override void OnApplyTemplate()
         {
             base.OnApplyTemplate();
 
+            // Add our WndProc hook.
+            HwndSource source = (HwndSource) PresentationSource.FromVisual(this);
+            source.AddHook(new HwndSourceHook(WndProcHook));
+
             Version1.Content = "SMXConfig version " + SMX.SMX.Version();
             Version2.Content = "SMXConfig version " + SMX.SMX.Version();
 
@@ -516,5 +513,21 @@ namespace smx_config
             // until we call dialog.Close above.
             dialog.ShowDialog();
         }
+
+        const int WM_SYSCOMMAND = 0x0112;
+        const int SC_MINIMIZE = 0xF020;
+        private IntPtr WndProcHook(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
+        {
+            App application = (App) Application.Current;
+
+            if(msg == WM_SYSCOMMAND && ((int)wparam & 0xFFF0) == SC_MINIMIZE)
+            {
+                // Cancel minimize, and call MinimizeToTray instead.
+                handled = true;
+                application.MinimizeToTray(); 
+            }
+
+            return IntPtr.Zero;
+        }
     }
 }