Screenshot: Fix the interactive dialog being visible in screenshots o…

…f the entire screen (#109)

src/Screenshot/Portal.vala

@@ -170,14 +170,16 @@ public class Screenshot.Portal : Object {
                     cancelled = false;
                 }
 
-                screenshot.callback ();
+                dialog.destroy ();
+
+                // When we close our window, gala fades us out so wait until we are actually not visible anymore
+                // (The animation duration in gala is currently 195ms)
+                Timeout.add_once (200, () => screenshot.callback ());
             });
 
             dialog.show ();
             yield;
 
-            dialog.destroy ();
-
             if (cancelled) {
                 response = 1;
                 return;