From b012a1397f5a523fcb78381fc0dd56701a5b60f6 Mon Sep 17 00:00:00 2001
From: Erik Darling <2136037+erikdarlingdata@users.noreply.github.com>
Date: Thu, 2 Apr 2026 09:37:21 -0400
Subject: [PATCH] Bring existing window to foreground on second launch instead
 of error
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Lite: Replace "already running" error dialog with FindWindow/
SetForegroundWindow to activate the existing instance. Only call
SW_RESTORE if the window is minimized (IsIconic) to preserve
maximized state.

Dashboard: Fix WndProc handler to only reset WindowState when
minimized, preserving maximized state on second-launch activation.

Both: Keep minimize-to-tray as a user setting — when enabled, the
window hides from the taskbar on minimize (restored via tray icon).

Fixes #769

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 Dashboard/MainWindow.xaml.cs |  5 +++--
 Lite/App.xaml.cs             | 28 +++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/Dashboard/MainWindow.xaml.cs b/Dashboard/MainWindow.xaml.cs
index 151d218b..396e8ebb 100644
--- a/Dashboard/MainWindow.xaml.cs
+++ b/Dashboard/MainWindow.xaml.cs
@@ -137,9 +137,10 @@ private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref b
         {
             if (msg == NativeMethods.WM_SHOWMONITOR)
             {
-                // Another instance tried to start - bring this window to front
+                // Another instance tried to start - bring this window to front (#769)
                 Show();
-                WindowState = WindowState.Normal;
+                if (WindowState == WindowState.Minimized)
+                    WindowState = WindowState.Normal;
                 Activate();
                 Topmost = true;  // Temporarily set topmost to ensure visibility
                 Topmost = false;
diff --git a/Lite/App.xaml.cs b/Lite/App.xaml.cs
index d4443041..4b2ba29b 100644
--- a/Lite/App.xaml.cs
+++ b/Lite/App.xaml.cs
@@ -22,6 +22,21 @@ public partial class App : Application
     [DllImport("shell32.dll", SetLastError = true)]
     private static extern void SetCurrentProcessExplicitAppUserModelID([MarshalAs(UnmanagedType.LPWStr)] string appId);
 
+    [DllImport("user32.dll")]
+    private static extern bool SetForegroundWindow(IntPtr hWnd);
+
+    [DllImport("user32.dll")]
+    private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
+
+    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
+    private static extern IntPtr FindWindow(string? lpClassName, string lpWindowName);
+
+    [DllImport("user32.dll")]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    private static extern bool IsIconic(IntPtr hWnd);
+
+    private const int SW_RESTORE = 9;
+
     private const string MutexName = "PerformanceMonitorLite_SingleInstance";
     private Mutex? _singleInstanceMutex;
     private bool _ownsMutex;
@@ -167,11 +182,14 @@ protected override void OnStartup(StartupEventArgs e)
 
         if (!_ownsMutex)
         {
-            MessageBox.Show(
-                "Performance Monitor Lite is already running.",
-                "Already Running",
-                MessageBoxButton.OK,
-                MessageBoxImage.Information);
+            /* Bring the existing instance's window to the foreground instead of showing an error (#769) */
+            var hWnd = FindWindow(null, "Performance Monitor Lite");
+            if (hWnd != IntPtr.Zero)
+            {
+                if (IsIconic(hWnd))
+                    ShowWindow(hWnd, SW_RESTORE);
+                SetForegroundWindow(hWnd);
+            }
             Shutdown();
             return;
         }