viewSelector: Avoid stealing focus from other entries into overview entry

The captured-event handler just redirects focus there on the first keypress,
what it doesn't account for is that other entries may be active while the
Activities overview is opened (eg. alt-f2, or other modal dialogs). Play
along with other entries, and make it only steal focus if no other entry
is selected.

https://gitlab.gnome.org/GNOME/gnome-shell/issues/33

Closes: #33

js/ui/viewSelector.js

@@ -606,7 +606,7 @@ var ViewSelector = new Lang.Class({
                 // - cancel the search
                 this.reset();
             }
-        } else if (!this._text.has_key_focus() &&
+        } else if (!(global.stage.get_key_focus() instanceof Clutter.Text) &&
                    (event.type() == Clutter.EventType.KEY_PRESS ||
                     event.type() == Clutter.EventType.KEY_RELEASE)) {
             let unichar = event.get_key_unicode();