Fix Explorer: move only targeted window, not all Explorer windows

Explorer uses a single process for all File Explorer windows, so the
sibling-grouping logic would grab every open Explorer window and try
to move them all. Some of those windows (on other desktops or shell
helper windows) fail with TYPE_E_ELEMENTNOTFOUND, causing a crash.

For explorer.exe, skip grouping and just move the one targeted window.
Also make secondary window move failures non-fatal for other apps.

Fixes #8

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: shanselman

.gitignore

@@ -18,3 +18,5 @@ packages/
 
 ## Publish output
 publish/
+
+mvd-debug.log

src/MaximizeToVirtualDesktop/FullScreenManager.cs

@@ -77,8 +77,22 @@ public void MaximizeToDesktop(IntPtr hwnd)
             return;
         }
 
-        // 1. Find all windows from the same process
-        var allWindows = GetAllProcessWindows(hwnd);
+        // 1. Find all windows to move together
+        // Explorer is a single-process app — all File Explorer windows share one process,
+        // so grouping by process would grab every Explorer window. Just move the targeted one.
+        NativeMethods.GetWindowThreadProcessId(hwnd, out int targetPid);
+        bool isExplorer = false;
+        try
+        {
+            using var proc = Process.GetProcessById(targetPid);
+            isExplorer = proc.ProcessName.Equals("explorer", StringComparison.OrdinalIgnoreCase);
+        }
+        catch { }
+
+        var allWindows = isExplorer
+            ? new List<IntPtr> { hwnd }
+            : GetAllProcessWindows(hwnd);
+
         if (allWindows.Count == 0)
         {
             Trace.WriteLine("FullScreenManager: No valid windows found for process, aborting.");
@@ -147,10 +161,10 @@ public void MaximizeToDesktop(IntPtr hwnd)
             {
                 movedWindows.Add(window);
             }
-            else
+            else if (window == hwnd)
             {
-                Trace.WriteLine($"FullScreenManager: Failed to move window {window}, rolling back.");
-                // Rollback: move already-moved windows back
+                // Primary window failed — must rollback
+                Trace.WriteLine($"FullScreenManager: Failed to move primary window {window}, rolling back.");
                 var origDesktop = _vds.FindDesktop(originalDesktopId.Value);
                 try
                 {
@@ -170,6 +184,11 @@ public void MaximizeToDesktop(IntPtr hwnd)
                 Marshal.ReleaseComObject(tempDesktop);
                 return;
             }
+            else
+            {
+                // Secondary window failed — skip it, not critical
+                Trace.WriteLine($"FullScreenManager: Skipping secondary window {window} (move failed).");
+            }
         }
 
         // 6. Switch to the new desktop

src/MaximizeToVirtualDesktop/VirtualDesktopService.cs

@@ -156,7 +156,7 @@ public bool MoveWindowToDesktop(IntPtr hwnd, IVirtualDesktop desktop)
         }
         catch (Exception ex)
         {
-            Trace.WriteLine($"VirtualDesktopService: MoveWindowToDesktop failed: {ex.Message}");
+            Trace.WriteLine($"VirtualDesktopService: MoveWindowToDesktop failed for hwnd={hwnd}: {ex.GetType().Name}: {ex.Message}");
             if (view != null) { Marshal.ReleaseComObject(view); view = null; }
 
             // Second attempt: try main window of the process