[gnome-shell] Increase the timeout for hiding the tray if the mouse didn't move far from it

[Marina Zhurakhinskaya <marinaz src gnome org>]

commit 3640a4dd1ebb786831b77789a0650436506d061c
Author: Hellyna Ng <helly helly tk>
Date:   Sun Oct 31 03:54:43 2010 +0800

    Increase the timeout for hiding the tray if the mouse didn't move far from it
    
    We shouldn't hide the tray as quickly if the user might have left it
    unintentionally, such as when moving the mouse over to a different tray item or
    using the scroll bar in the chat notification.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=630767

 js/ui/messageTray.js |   39 +++++++++++++++++++++++++++++++++------
 1 files changed, 33 insertions(+), 6 deletions(-)
---
diff --git a/js/ui/messageTray.js b/js/ui/messageTray.js
index e0561cb..7ab1b76 100644
--- a/js/ui/messageTray.js
+++ b/js/ui/messageTray.js
@@ -26,6 +26,10 @@ const BUTTON_ICON_SIZE = 36;
 
 const MAX_SOURCE_TITLE_WIDTH = 180;
 
+// We delay hiding of the tray if the mouse is within MOUSE_LEFT_ACTOR_THRESHOLD
+// range from the point where it left the tray.
+const MOUSE_LEFT_ACTOR_THRESHOLD = 20;
+
 const State = {
     HIDDEN:  0,
     SHOWING: 1,
@@ -1146,6 +1150,8 @@ MessageTray.prototype = {
             if (this._trayLeftTimeoutId) {
                 Mainloop.source_remove(this._trayLeftTimeoutId);
                 this._trayLeftTimeoutId = 0;
+                this._trayLeftMouseX = -1;
+                this._trayLeftMouseY = -1;
                 return;
             }
 
@@ -1167,6 +1173,14 @@ MessageTray.prototype = {
             this._pointerInTray = true;
             this._updateState();
         } else {
+            // We record the position of the mouse the moment it leaves the tray. These coordinates are used in
+            // this._onTrayLeftTimeout() to determine if the mouse has moved far enough during the initial timeout for us
+            // to consider that the user intended to leave the tray and therefore hide the tray. If the mouse is still
+            // close to its previous position, we extend the timeout once.
+            let [x, y, mods] = global.get_pointer();
+            this._trayLeftMouseX = x;
+            this._trayLeftMouseY = y;
+
             // We wait just a little before hiding the message tray in case the user quickly moves the mouse back into it.
             // We wait for a longer period if the notification popped up where the mouse pointer was already positioned.
             // That gives the user more time to mouse away from the notification and mouse back in in order to expand it.
@@ -1176,12 +1190,25 @@ MessageTray.prototype = {
     },
 
     _onTrayLeftTimeout: function() {
-        this._useLongerTrayLeftTimeout = false;
-        this._trayLeftTimeoutId = 0;
-        this._pointerInTray = false;
-        this._pointerInSummary = false;
-        this._updateNotificationTimeout(0);
-        this._updateState();
+        let [x, y, mods] = global.get_pointer();
+        // We extend the timeout once if the mouse moved no further than MOUSE_LEFT_ACTOR_THRESHOLD to either side or up.
+        // We don't check how far down the mouse moved because any point above the tray, but below the exit coordinate,
+        // is close to the tray.
+        if (this._trayLeftMouseX > -1 &&
+            y > this._trayLeftMouseY - MOUSE_LEFT_ACTOR_THRESHOLD &&
+            x < this._trayLeftMouseX + MOUSE_LEFT_ACTOR_THRESHOLD &&
+            x > this._trayLeftMouseX - MOUSE_LEFT_ACTOR_THRESHOLD) {
+            this._trayLeftMouseX = -1;
+            this._trayLeftTimeoutId = Mainloop.timeout_add(LONGER_HIDE_TIMEOUT * 1000,
+                                                             Lang.bind(this, this._onTrayLeftTimeout));
+        } else {
+            this._trayLeftTimeoutId = 0;
+            this._useLongerTrayLeftTimeout = false;
+            this._pointerInTray = false;
+            this._pointerInSummary = false;
+            this._updateNotificationTimeout(0);
+            this._updateState();
+        }
         return false;
     },