diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index 140a408..54ae2d4 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -171,6 +171,11 @@ public partial class MainWindow : Window
     /// </summary>
     private void MainWindow_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
     {
+        // ⛔ e.IsRepeat matters: Windows auto-repeats a held modifier. Creation holds Ctrl (the
+        // chord is Ctrl+right-click), so without this guard the repeat tick ~500 ms later saw an
+        // open box and closed it — the box appeared and vanished as it was created.
+        if (e.IsRepeat) return;
+
         if (e.Key is System.Windows.Input.Key.LeftCtrl or System.Windows.Input.Key.RightCtrl
             && _viewModel.IsZoomActive)
         {