[gnome-shell] windowManager: Only allow top-drag gesture if focus window is fullscreen

[Florian Müllner <fmuellner src gnome org>]

commit c1d3e304cba3222f0a8f2618d20b489ca5baca76
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Sat Feb 9 23:40:02 2019 +0100

    windowManager: Only allow top-drag gesture if focus window is fullscreen
    
    The top drag gesture is not of any use if the topmost window is not
    a fullscreen window and will only block events near the important top
    screen edge (i.e. the panel). To fix this, only enable this gesture if
    the focus window is a fullscreen window.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/552

 js/ui/windowManager.js | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index 98bed26f2..ea9493d6f 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -1076,6 +1076,15 @@ var WindowManager = class {
             if (currentWindow)
                 currentWindow.unmake_fullscreen();
         });
+
+        let updateUnfullscreenGesture = () => {
+            let currentWindow = global.display.focus_window;
+            gesture.enabled = currentWindow && currentWindow.is_fullscreen();
+        }
+
+        global.display.connect('notify::focus-window', updateUnfullscreenGesture);
+        global.display.connect('in-fullscreen-changed', updateUnfullscreenGesture);
+
         global.stage.add_action(gesture);
     }