fix: don't assign NSAlert to window which is not visible (electron#23089)

trop[bot] · CezaryKulakowski · John Kleinschmidt · web-flow · commit 97010bf947c6 · 2020-04-14T10:57:22.000-04:00
* fix: don't assign NSAlert to window which is not visible

Without this change it's possible to create message box which can't
be dismissed on mac.

* fixup! fix: don't assign NSAlert to window which is not visible

* fixup! fix: don't assign NSAlert to window which is not visible

* Update docs/api/dialog.md

Co-authored-by: Cezary Kulakowski &lt;cezary@openfin.co&gt;
Co-authored-by: John Kleinschmidt &lt;jkleinsc@github.com&gt;
diff --git a/docs/api/dialog.md b/docs/api/dialog.md
@@ -254,6 +254,7 @@ Shows a message box, it will block the process until the message box is closed.
 It returns the index of the clicked button.
 
 The `browserWindow` argument allows the dialog to attach itself to a parent window, making it modal.
+If the `browserWindow` is not shown, the dialog will not be attached to it. In that case it will be displayed as an independent window.
 
 ### `dialog.showMessageBox([browserWindow, ]options)`
 
diff --git a/shell/browser/ui/message_box_mac.mm b/shell/browser/ui/message_box_mac.mm
@@ -97,8 +97,10 @@ int ShowMessageBoxSync(const MessageBoxSettings& settings) {
   NSAlert* alert = CreateNSAlert(settings);
 
   // Use runModal for synchronous alert without parent, since we don't have a
-  // window to wait for.
-  if (!settings.parent_window)
+  // window to wait for. Also use it when window is provided but it is not
+  // shown as it would be impossible to dismiss the alert if it is connected
+  // to invisible window (see #22671).
+  if (!settings.parent_window || !settings.parent_window->IsVisible())
     return [[alert autorelease] runModal];
 
   __block int ret_code = -1;
