Revert "ui: Remove maybe_redirect_mouse_event"

This reverts commit 6c7a51378f.

It seems we still have issues with GDK's grab tracking getting confused.
That's unfortunate.

src/ui/ui.c

@@ -37,6 +37,13 @@ struct _MetaUI
   Display *xdisplay;
   Screen *xscreen;
   MetaFrames *frames;
+
+  /* For double-click tracking */
+  gint button_click_number;
+  Window button_click_window;
+  int button_click_x;
+  int button_click_y;
+  guint32 button_click_time;
 };
 
 void
@@ -65,6 +72,183 @@ meta_ui_get_screen_number (void)
   return gdk_screen_get_number (gdk_screen_get_default ());
 }
 
+/* For XInput2 */
+#include "display-private.h"
+
+static gboolean
+is_input_event (XEvent *event)
+{
+  MetaDisplay *display = meta_get_display ();
+
+  return (event->type == GenericEvent &&
+          event->xcookie.extension == display->xinput_opcode);
+}
+
+/* We do some of our event handling in frames.c, which expects
+ * GDK events delivered by GTK+.  However, since the transition to
+ * client side windows, we can't let GDK see button events, since the
+ * client-side tracking of implicit and explicit grabs it does will
+ * get confused by our direct use of X grabs in the core code.
+ *
+ * So we do a very minimal GDK => GTK event conversion here and send on the
+ * events we care about, and then filter them out so they don't go
+ * through the normal GDK event handling.
+ *
+ * To reduce the amount of code, the only events fields filled out
+ * below are the ones that frames.c uses. If frames.c is modified to
+ * use more fields, more fields need to be filled out below.
+ */
+
+static gboolean
+maybe_redirect_mouse_event (XEvent *xevent)
+{
+  GdkDisplay *gdisplay;
+  GdkDeviceManager *gmanager;
+  GdkDevice *gdevice;
+  MetaUI *ui;
+  GdkEvent *gevent;
+  GdkWindow *gdk_window;
+  Window window;
+  XIEvent *xev;
+  XIDeviceEvent *xev_d = NULL;
+  XIEnterEvent *xev_e = NULL;
+
+  if (!is_input_event (xevent))
+    return FALSE;
+
+  xev = (XIEvent *) xevent->xcookie.data;
+
+  switch (xev->evtype)
+    {
+    case XI_TouchBegin:
+    case XI_ButtonPress:
+    case XI_ButtonRelease:
+    case XI_Motion:
+      xev_d = (XIDeviceEvent *) xev;
+      window = xev_d->event;
+      break;
+    case XI_Enter:
+    case XI_Leave:
+      xev_e = (XIEnterEvent *) xev;
+      window = xev_e->event;
+      break;
+    default:
+      return FALSE;
+    }
+
+  gdisplay = gdk_x11_lookup_xdisplay (xev->display);
+  ui = g_object_get_data (G_OBJECT (gdisplay), "meta-ui");
+  if (!ui)
+    return FALSE;
+
+  gdk_window = gdk_x11_window_lookup_for_display (gdisplay, window);
+  if (gdk_window == NULL)
+    return FALSE;
+
+  gmanager = gdk_display_get_device_manager (gdisplay);
+  gdevice = gdk_x11_device_manager_lookup (gmanager, META_VIRTUAL_CORE_POINTER_ID);
+
+  /* If GDK already thinks it has a grab, we better let it see events; this
+   * is the menu-navigation case and events need to get sent to the appropriate
+   * (client-side) subwindow for individual menu items.
+   */
+  if (gdk_display_device_is_grabbed (gdisplay, gdevice))
+    return FALSE;
+
+  switch (xev->evtype)
+    {
+    case XI_TouchBegin:
+    case XI_ButtonPress:
+    case XI_ButtonRelease:
+      if (xev_d->evtype == XI_ButtonPress || xev_d->evtype == XI_TouchBegin)
+        {
+          GtkSettings *settings = gtk_settings_get_default ();
+          int double_click_time;
+          int double_click_distance;
+          int button;
+
+          g_object_get (settings,
+                        "gtk-double-click-time", &double_click_time,
+                        "gtk-double-click-distance", &double_click_distance,
+                        NULL);
+
+          if (xev->evtype == XI_TouchBegin)
+            button = 1;
+          else
+            button = xev_d->detail;
+
+          if (button == ui->button_click_number &&
+              xev_d->event == ui->button_click_window &&
+              xev_d->time < ui->button_click_time + double_click_time &&
+              ABS (xev_d->event_x - ui->button_click_x) <= double_click_distance &&
+              ABS (xev_d->event_y - ui->button_click_y) <= double_click_distance)
+            {
+              gevent = gdk_event_new (GDK_2BUTTON_PRESS);
+
+              ui->button_click_number = 0;
+            }
+          else
+            {
+              gevent = gdk_event_new (GDK_BUTTON_PRESS);
+              ui->button_click_number = button;
+              ui->button_click_window = xev_d->event;
+              ui->button_click_time = xev_d->time;
+              ui->button_click_x = xev_d->event_x;
+              ui->button_click_y = xev_d->event_y;
+            }
+
+          gevent->button.button = button;
+        }
+      else
+        {
+          gevent = gdk_event_new (GDK_BUTTON_RELEASE);
+          gevent->button.button = xev_d->detail;
+        }
+
+      gevent->button.window = g_object_ref (gdk_window);
+      gevent->button.time = xev_d->time;
+      gevent->button.x = xev_d->event_x;
+      gevent->button.y = xev_d->event_y;
+      gevent->button.x_root = xev_d->root_x;
+      gevent->button.y_root = xev_d->root_y;
+
+      break;
+    case XI_Motion:
+      gevent = gdk_event_new (GDK_MOTION_NOTIFY);
+      gevent->motion.type = GDK_MOTION_NOTIFY;
+      gevent->motion.window = g_object_ref (gdk_window);
+      break;
+    case XI_Enter:
+    case XI_Leave:
+      gevent = gdk_event_new (xev_e->evtype == XI_Enter ? GDK_ENTER_NOTIFY : GDK_LEAVE_NOTIFY);
+      gevent->crossing.window = g_object_ref (gdk_window);
+      gevent->crossing.x = xev_e->event_x;
+      gevent->crossing.y = xev_e->event_y;
+      break;
+    default:
+      g_assert_not_reached ();
+      break;
+    }
+
+  /* If we've gotten here, we've created the gdk_event and should send it on */
+  gdk_event_set_device (gevent, gdevice);
+  gtk_main_do_event (gevent);
+  gdk_event_free (gevent);
+
+  return TRUE;
+}
+
+static GdkFilterReturn
+ui_filter_func (GdkXEvent *xevent,
+                GdkEvent *event,
+                gpointer data)
+{
+  if (maybe_redirect_mouse_event (xevent))
+    return GDK_FILTER_REMOVE;
+  else
+    return GDK_FILTER_CONTINUE;
+}
+
 MetaUI*
 meta_ui_new (Display *xdisplay,
              Screen  *screen)
@@ -88,13 +272,25 @@ meta_ui_new (Display *xdisplay,
    */
   gtk_widget_show (GTK_WIDGET (ui->frames));
 
+  gdk_window_add_filter (NULL, ui_filter_func, NULL);
+
+  g_object_set_data (G_OBJECT (gdisplay), "meta-ui", ui);
+
   return ui;
 }
 
 void
 meta_ui_free (MetaUI *ui)
 {
+  GdkDisplay *gdisplay;
+
   gtk_widget_destroy (GTK_WIDGET (ui->frames));
+
+  gdisplay = gdk_x11_lookup_xdisplay (ui->xdisplay);
+  g_object_set_data (G_OBJECT (gdisplay), "meta-ui", NULL);
+
+  gdk_window_remove_filter (NULL, ui_filter_func, NULL);
+
   g_free (ui);
 }