Fix duplication of codebox toolbar callbacks (#2635)

The `update_toolbar_buttons` function, which is called whenever a
codebox is reconfigured or when codebox toolbars are en-/disabled, works
by removing all the toolbar buttons and readding them as necessary.  It
was using the `_toolbar.append()` function which sets up the buttons'
callback at the same time.  Because the ToolbarButton objects are
persistent, an extra copy of the callback was being connected each time
the button was removed and readded, so Gtk thought we wanted to run it
multiple times.

Now, the buttons' callbacks are setup once using
`signal_clicked().connect()` in the codebox constructor and the
`update_toolbar_buttons` function uses `_toolbar.insert()` which doesn't
affect the callbacks at all.

Fixes #2628

src/ct/ct_codebox.cc

@@ -202,6 +202,24 @@ CtCodebox::CtCodebox(CtMainWin* pCtMainWin,
     g_signal_connect(G_OBJECT(_ctTextview.gobj()), "cut-clipboard", G_CALLBACK(CtClipboard::on_cut_clipboard), _uCtPairCodeboxMainWin.get());
     g_signal_connect(G_OBJECT(_ctTextview.gobj()), "copy-clipboard", G_CALLBACK(CtClipboard::on_copy_clipboard), _uCtPairCodeboxMainWin.get());
     g_signal_connect(G_OBJECT(_ctTextview.gobj()), "paste-clipboard", G_CALLBACK(CtClipboard::on_paste_clipboard), _uCtPairCodeboxMainWin.get());
+    _toolButtonPlay.signal_clicked().connect([this](){
+        CtActions* pCtActions = _pCtMainWin->get_ct_actions();
+        pCtActions->curr_codebox_anchor = this;
+        pCtActions->object_set_selection(this);
+        pCtActions->exec_code_all();
+    });
+    _toolButtonCopy.signal_clicked().connect([this](){
+        CtActions* pCtActions = _pCtMainWin->get_ct_actions();
+        pCtActions->curr_codebox_anchor = this;
+        pCtActions->object_set_selection(this);
+        pCtActions->codebox_copy_content();
+    });
+    _toolButtonProp.signal_clicked().connect([this](){
+        CtActions* pCtActions = _pCtMainWin->get_ct_actions();
+        pCtActions->curr_codebox_anchor = this;
+        pCtActions->object_set_selection(this);
+        pCtActions->codebox_change_properties();
+    });
 }
 
 void CtCodebox::update_toolbar_buttons()
@@ -214,31 +232,16 @@ void CtCodebox::update_toolbar_buttons()
             _toolButtonPlay.set_icon_name("ct_play");
             _toolButtonPlay.set_label(label_n_tooltip);
             _toolButtonPlay.set_tooltip_text(label_n_tooltip);
-            _toolbar.append(_toolButtonPlay, [this](){
-                CtActions* pCtActions = _pCtMainWin->get_ct_actions();
-                pCtActions->curr_codebox_anchor = this;
-                pCtActions->object_set_selection(this);
-                pCtActions->exec_code_all();
-            });
+            _toolbar.insert(_toolButtonPlay, -1);
         }
         _toolButtonCopy.set_icon_name("ct_edit_copy");
         _toolButtonCopy.set_label("Copy Code");
         _toolButtonCopy.set_tooltip_text("Copy Code");
-        _toolbar.append(_toolButtonCopy, [this](){
-            CtActions* pCtActions = _pCtMainWin->get_ct_actions();
-            pCtActions->curr_codebox_anchor = this;
-            pCtActions->object_set_selection(this);
-            pCtActions->codebox_copy_content();
-        });
+        _toolbar.insert(_toolButtonCopy, -1);
         _toolButtonProp.set_icon_name("ct_codebox_edit");
         _toolButtonProp.set_label(_("Change CodeBox Properties"));
         _toolButtonProp.set_tooltip_text(_("Change CodeBox Properties"));
-        _toolbar.append(_toolButtonProp, [this](){
-            CtActions* pCtActions = _pCtMainWin->get_ct_actions();
-            pCtActions->curr_codebox_anchor = this;
-            pCtActions->object_set_selection(this);
-            pCtActions->codebox_change_properties();
-        });
+        _toolbar.insert(_toolButtonProp, -1);
     }
 }