diff -up firefox-68.0/widget/gtk/nsWindow.cpp.1196777 firefox-68.0/widget/gtk/nsWindow.cpp
--- firefox-68.0/widget/gtk/nsWindow.cpp.1196777	2019-05-21 11:29:55.833376744 +0200
+++ firefox-68.0/widget/gtk/nsWindow.cpp	2019-05-21 12:15:35.446089316 +0200
@@ -156,7 +156,8 @@ const gint kEvents =
 #if GTK_CHECK_VERSION(3, 4, 0)
     GDK_SMOOTH_SCROLL_MASK | GDK_TOUCH_MASK |
 #endif
-    GDK_SCROLL_MASK | GDK_POINTER_MOTION_MASK | GDK_PROPERTY_CHANGE_MASK;
+    GDK_SCROLL_MASK | GDK_POINTER_MOTION_MASK | GDK_PROPERTY_CHANGE_MASK |
+    GDK_FOCUS_CHANGE_MASK;
 
 #if !GTK_CHECK_VERSION(3, 22, 0)
 typedef enum {