windowManager: Undim parent when minimizing attached modal

Minimizing modal dialogs is highly unconventional - and in fact
disabled in our own code - but apps can still do it programmatically.

The parent window shouldn't remain dimmed in that case, so make
sure to re-check dimming when minimizing an attached modal.

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5581

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2337>

js/ui/windowManager.js

@@ -1141,6 +1141,10 @@ var WindowManager = class {
     }
 
     _minimizeWindow(shellwm, actor) {
+        const window = actor.meta_window;
+        if (window.is_attached_dialog())
+            this._checkDimming(window.get_transient_for());
+
         const types = [
             Meta.WindowType.NORMAL,
             Meta.WindowType.MODAL_DIALOG,