the merge id for the merged UI, see gtk_ui_manager_new_merge_id()
a path
the name for the added UI element
the name of the action to be proxied, or %NULL to add a separator
the type of UI element to add.
if %TRUE, the UI element is added before its siblings, otherwise it is added after its siblings.
2.4
Adds a UI element to the current contents of @manager.
If @type is %GTK_UI_MANAGER_AUTO, GTK+ inserts a menuitem, toolitem or separator if such an element can be inserted at the place determined by @path. Otherwise @type must indicate an element that can be inserted at the place determined by @path.
If @path points to a menuitem or toolitem, the new element will be inserted before or after this item, depending on @top.