Change the shortcut to Ctrl+Shift+Backspace

Ctrl+Backspace is used to delete word backwards in text entry boxes, and
I use it a lot.

CHANGES.rst

@@ -40,7 +40,7 @@ Changelog
 - Grouped task entries can now be sorted by start date, name, duration or
   according to tasks.txt order (GH: #228).
 
-- Add the ability to change the last entry using Primary+BackSpace (GH: #247).
+- Add the ability to change the last entry using Ctrl+Shift+BackSpace (GH: #247).
 
 
 0.11.3 (2019-04-23)

src/gtimelog/main.py

@@ -295,7 +295,7 @@ def do_startup(self):
         self.set_accels_for_action("win.go-home", ["<Alt>Home"])
         self.set_accels_for_action("win.focus-task-entry", ["<Primary>L"])
         self.set_accels_for_action("app.edit-log", ["<Primary>E"])
-        self.set_accels_for_action("app.edit-last-item", ["<Primary>BackSpace"])
+        self.set_accels_for_action("app.edit-last-item", ["<Primary><Shift>BackSpace"])
         self.set_accels_for_action("app.edit-tasks", ["<Primary>T"])
         self.set_accels_for_action("app.shortcuts", ["<Primary>question"])
         self.set_accels_for_action("app.preferences", ["<Primary>P"])

src/gtimelog/shortcuts.ui

@@ -145,7 +145,7 @@
             <child>
               <object class="GtkShortcutsShortcut">
                 <property name="visible">True</property>
-                <property name="accelerator">&lt;primary&gt;BackSpace</property>
+                <property name="accelerator">&lt;primary&gt;&lt;shift&gt;BackSpace</property>
                 <property name="title" translatable="yes" context="shortcut window">Edit last task entry</property>
               </object>
             </child>