Add go-to-line menu item and shortcut support

This is bound to Ctrl+I for parity with gedit and Builder. This is
starting to become a good argument for swappable keybinding support.

Author: kaiw

data/ui/meldapp-ui.xml

@@ -26,6 +26,8 @@
       <menuitem action="FindNext"/>
       <menuitem action="FindPrevious"/>
       <menuitem action="Replace"/>
+      <separator/>
+      <menuitem action="GoToLine"/>
     </menu>
     <menu action="ChangesMenu">
       <menuitem action="PrevChange"/>

meld/filediff.py

@@ -959,6 +959,10 @@ def on_find_next_activate(self, *args):
     def on_find_previous_activate(self, *args):
         self.findbar.start_find_previous(self.focus_pane)
 
+    @with_focused_pane
+    def on_go_to_line_activate(self, pane, *args):
+        self.statusbar[pane].emit('start-go-to-line')
+
     def on_scrolledwindow_size_allocate(self, scrolledwindow, allocation):
         index = self.scrolledwindow.index(scrolledwindow)
         if index == 0 or index == 1:

meld/meldwindow.py

@@ -82,6 +82,9 @@ def __init__(self):
                 _("_Replace…"), "<Primary>H",
                 _("Find and replace text"),
                 self.on_menu_replace_activate),
+            ("GoToLine", None, _("Go to _Line"), "<Primary>I",
+                _("Go to a specific line"),
+                self.on_menu_go_to_line_activate),
 
             ("ChangesMenu", None, _("_Changes")),
             ("NextChange", Gtk.STOCK_GO_DOWN, _("Next Change"), "<Alt>Down",
@@ -446,6 +449,9 @@ def on_menu_find_previous_activate(self, *extra):
     def on_menu_replace_activate(self, *extra):
         self.current_doc().on_replace_activate()
 
+    def on_menu_go_to_line_activate(self, *extra):
+        self.current_doc().on_go_to_line_activate()
+
     def on_menu_copy_activate(self, *extra):
         widget = self.widget.get_focus()
         if isinstance(widget, Gtk.Editable):

meld/ui/statusbar.py

@@ -103,6 +103,8 @@ class MeldStatusBar(Gtk.Statusbar):
     __gtype_name__ = "MeldStatusBar"
 
     __gsignals__ = {
+        'start-go-to-line': (
+            GObject.SignalFlags.ACTION, None, tuple()),
         'go-to-line': (
             GObject.SignalFlags.RUN_FIRST, None, (int,)),
         'encoding-changed': (
@@ -205,6 +207,7 @@ def format_cursor_position(binding, cursor):
         self.bind_property(
             'cursor_position', button, 'label', GObject.BindingFlags.DEFAULT,
             format_cursor_position)
+        self.connect('start-go-to-line', lambda *args: button.clicked())
         button.set_popover(pop)
         button.show()