Express tool position rectangle position consistently

Use tool position as offset from group position and not vice versa, both
because this was already done like this in the other places and because
this makes more sense: the tool is inside the group, so its position is
relative to it.

No real changes.

src/ribbon/toolbar.cpp

@@ -439,7 +439,7 @@ wxRibbonToolBarToolBase* wxRibbonToolBar::GetToolByPos(wxCoord x, wxCoord y)cons
         for ( size_t t = 0; t < tool_count; ++t )
         {
             wxRibbonToolBarToolBase* tool = group->tools.Item(t);
-            wxRect rect(tool->position + group->position, tool->size);
+            wxRect rect(group->position + tool->position, tool->size);
             if(rect.Contains(x, y))
             {
                 return tool;
@@ -535,7 +535,7 @@ wxRect wxRibbonToolBar::GetToolRect(int tool_id)const
             wxRibbonToolBarToolBase* tool = group->tools.Item(t);
             if (tool->id == tool_id)
             {
-                return wxRect(tool->position + group->position, tool->size);
+                return wxRect(group->position + tool->position, tool->size);
             }
             ++pos;
         }