diff -up firefox-86.0/widget/gtk/nsWindow.cpp.1196777 firefox-86.0/widget/gtk/nsWindow.cpp
--- firefox-86.0/widget/gtk/nsWindow.cpp.1196777	2021-02-23 17:52:42.291702566 +0100
+++ firefox-86.0/widget/gtk/nsWindow.cpp	2021-02-23 17:57:52.434895984 +0100
@@ -195,7 +195,8 @@ const gint kEvents = GDK_TOUCHPAD_GESTUR
                      GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK |
                      GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
                      GDK_SMOOTH_SCROLL_MASK | GDK_TOUCH_MASK | GDK_SCROLL_MASK |
-                     GDK_POINTER_MOTION_MASK | GDK_PROPERTY_CHANGE_MASK;
+                     GDK_POINTER_MOTION_MASK | GDK_PROPERTY_CHANGE_MASK |
+                     GDK_FOCUS_CHANGE_MASK;
 
 #if !GTK_CHECK_VERSION(3, 22, 0)
 typedef enum {