use Qt signals to manage calls to gh_manager functions in Qt graphics toolkit Limit access to the gh_manager object to the qt_graphics_toolkit class by using Qt signals to pass gh_manager events from individual graphics objects up to the qt_graphics_toolkit object. From there, we can make calls to the gh_manager object. * qt-graphics-toolkit.h, qt-graphics-toolkit.cc (qt_graphics_toolkit::gh_callback_event, qt_graphics_toolkit::gh_set_event): New slots. (qt_graphics_toolkit::create_object): Connect Object::gh_callback_event and Object::gh_set_event signals to qt_graphics_toolkit::gh_callback_event and qt_graphics_toolkit::gh_set_event slots. * BaseControl.cc, ButtonControl.cc, ButtonGroup.cc, Canvas.cc, ContextMenu.cc, EditControl.cc, Figure.cc, ListBoxControl.cc, Menu.cc, PopupMenuControl.cc, PushTool.cc, SliderControl.cc, Table.cc, ToggleTool.cc: Emit gh_callback_event and gh_set_event signals instead of calling gh_manager functions directly. * Object.h (Object::gh_callback_event, Object::gh_set_event): New signals. * Canvas.h (Canvas::gh_callback_event, Canvas::gh_set_event): New signals. * Container.h (Container::gh_callback_event, Container::gh_set_event): New signals.

--- a/libgui/graphics/ButtonGroup.cc	Fri Aug 02 14:28:48 2019 -0500
+++ b/libgui/graphics/ButtonGroup.cc	Fri Aug 02 15:19:43 2019 -0500
@@ -469,8 +469,8 @@
           }
 
         if (oldValue != newValue)
-          gh_manager::post_set (m_handle, "selectedobject", newValue.as_octave_value (),
-                                false);
+          emit gh_set_event (m_handle, "selectedobject",
+                             newValue.as_octave_value (), false);
       }
   }
 
@@ -496,8 +496,8 @@
         eventData.setfield ("Source", bp.get___myhandle__ ().as_octave_value ());
         eventData.setfield ("EventName", "SelectionChanged");
         octave_value selectionChangedEventObject (new octave_struct (eventData));
-        gh_manager::post_callback (m_handle, "selectionchangedfcn",
-                                   selectionChangedEventObject);
+        emit gh_callback_event (m_handle, "selectionchangedfcn",
+                                selectionChangedEventObject);
       }
   }