From 08494f86a062713ca99f71a0cc29bde9e762592c Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Tue, 3 Mar 2015 22:17:58 +0100
Subject: [PATCH] widget: Improve hack to ignore drags from widgets using
 motion events

Postpone until the last moment whether the target widget still
potentially uses updates from this sequence, or window dragging
actually applies because all gestures on the target went to denied
state.

This fixes window dragging on empty space in a headerbar that is
contained in a paned (as in e.g. gedit).

https://bugzilla.gnome.org/show_bug.cgi?id=745562
---
 gtk/gtkwidget.c        | 12 +++++++-----
 gtk/gtkwidgetprivate.h |  3 ++-
 gtk/gtkwindow.c        | 29 +++++++++++++++++------------
 3 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index c50b68476e..715105d9a7 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -17284,7 +17284,8 @@ _gtk_widget_list_controllers (GtkWidget           *widget,
 }
 
 gboolean
-_gtk_widget_consumes_motion (GtkWidget *widget)
+_gtk_widget_consumes_motion (GtkWidget        *widget,
+                             GdkEventSequence *sequence)
 {
   EventControllerData *data;
   GtkWidgetPrivate *priv;
@@ -17301,10 +17302,11 @@ _gtk_widget_consumes_motion (GtkWidget *widget)
       if (data->controller == NULL)
         continue;
 
-      if (!GTK_IS_GESTURE_SINGLE (data->controller))
-        return TRUE;
-      else if (GTK_IS_GESTURE_DRAG (data->controller) ||
-               GTK_IS_GESTURE_SWIPE (data->controller))
+      if ((!GTK_IS_GESTURE_SINGLE (data->controller) ||
+           GTK_IS_GESTURE_DRAG (data->controller) ||
+           GTK_IS_GESTURE_SWIPE (data->controller)) &&
+          gtk_gesture_get_sequence_state (GTK_GESTURE (data->controller),
+                                          sequence) != GTK_EVENT_SEQUENCE_DENIED)
         return TRUE;
     }
 
diff --git a/gtk/gtkwidgetprivate.h b/gtk/gtkwidgetprivate.h
index 676d6e856c..7f121aa128 100644
--- a/gtk/gtkwidgetprivate.h
+++ b/gtk/gtkwidgetprivate.h
@@ -160,7 +160,8 @@ void              _gtk_widget_remove_controller            (GtkWidget
                                                             GtkEventController  *controller);
 GList *           _gtk_widget_list_controllers             (GtkWidget           *widget,
                                                             GtkPropagationPhase  phase);
-gboolean          _gtk_widget_consumes_motion              (GtkWidget           *widget);
+gboolean          _gtk_widget_consumes_motion              (GtkWidget           *widget,
+                                                            GdkEventSequence    *sequence);
 
 gboolean          gtk_widget_has_tick_callback             (GtkWidget *widget);
 
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index ba79229d6b..92d7a03cde 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -1509,7 +1509,6 @@ drag_gesture_begin_cb (GtkGestureDrag *gesture,
   GdkEventSequence *sequence;
   GtkWindowRegion region;
   const GdkEvent *event;
-  GtkWidget *event_widget;
 
   sequence = gtk_gesture_single_get_current_sequence (GTK_GESTURE_SINGLE (gesture));
   event = gtk_gesture_get_last_event (GTK_GESTURE (gesture), sequence);
@@ -1517,19 +1516,10 @@ drag_gesture_begin_cb (GtkGestureDrag *gesture,
   if (!event)
     return;
 
-  event_widget = gtk_get_event_widget ((GdkEvent *) event);
+  region = get_active_region_type (window, (GdkEventAny*) event, x, y);
 
-  if (event_widget != GTK_WIDGET (window) &&
-      !gtk_widget_has_grab (event_widget) &&
-      _gtk_widget_consumes_motion (event_widget))
+  if (region != GTK_WINDOW_REGION_TITLE)
     gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_DENIED);
-  else
-    {
-      region = get_active_region_type (window, (GdkEventAny*) event, x, y);
-
-      if (region != GTK_WINDOW_REGION_TITLE)
-        gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_DENIED);
-    }
 }
 
 static void
@@ -1549,8 +1539,23 @@ drag_gesture_update_cb (GtkGestureDrag *gesture,
   if (ABS (offset_x) > double_click_distance ||
       ABS (offset_y) > double_click_distance)
     {
+      GdkEventSequence *sequence;
       gdouble start_x, start_y;
       gint x_root, y_root;
+      const GdkEvent *event;
+      GtkWidget *event_widget;
+
+      sequence = gtk_gesture_single_get_current_sequence (GTK_GESTURE_SINGLE (gesture));
+      event = gtk_gesture_get_last_event (GTK_GESTURE (gesture), sequence);
+      event_widget = gtk_get_event_widget ((GdkEvent *) event);
+
+      if (event_widget != GTK_WIDGET (window) &&
+          !gtk_widget_has_grab (event_widget) &&
+          _gtk_widget_consumes_motion (event_widget, sequence))
+        {
+          gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_DENIED);
+          return;
+        }
 
       gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);