[gnome-shell] ibusCandidatePopup: Handle relative cursor signal absence gracefully

[Rui Matos <rtcm src gnome org>]

commit 1bf27b1f188a01d917c1133ff1b7ee0abadf98b7
Author: Rui Matos <tiagomatos gmail com>
Date:   Wed Feb 17 17:54:52 2016 +0100

    ibusCandidatePopup: Handle relative cursor signal absence gracefully
    
    Only recent IBus versions have support for this signal
    which is used for wayland clients. In order to work
    with older IBus versions we can silently ignore the
    signal's absence.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=753476

 js/ui/ibusCandidatePopup.js |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)
---
diff --git a/js/ui/ibusCandidatePopup.js b/js/ui/ibusCandidatePopup.js
index 5aedc86..05875a8 100644
--- a/js/ui/ibusCandidatePopup.js
+++ b/js/ui/ibusCandidatePopup.js
@@ -160,13 +160,20 @@ const CandidatePopup = new Lang.Class({
                              Lang.bind(this, function(ps, x, y, w, h) {
                                  this._setDummyCursorGeometry(x, y, w, h);
                              }));
-        panelService.connect('set-cursor-location-relative',
-                             Lang.bind(this, function(ps, x, y, w, h) {
-                                 if (!global.display.focus_window)
-                                     return;
-                                 let window = global.display.focus_window.get_compositor_private();
-                                 this._setDummyCursorGeometry(window.x + x, window.y + y, w, h);
-                             }));
+        try {
+            panelService.connect('set-cursor-location-relative',
+                                 Lang.bind(this, function(ps, x, y, w, h) {
+                                     if (!global.display.focus_window)
+                                         return;
+                                     let window = global.display.focus_window.get_compositor_private();
+                                     this._setDummyCursorGeometry(window.x + x, window.y + y, w, h);
+                                 }));
+        } catch(e) {
+            // Only recent IBus versions have support for this signal
+            // which is used for wayland clients. In order to work
+            // with older IBus versions we can silently ignore the
+            // signal's absence.
+        }
         panelService.connect('update-preedit-text',
                              Lang.bind(this, function(ps, text, cursorPosition, visible) {
                                  this._preeditText.visible = visible;