Introduced to increase support for Imaging Annotations.
When ObjBoxHighlight is true, it makes a filled box as a highlight box (highlight the background with the fill color).
hobj is the ID of the object. You can also specify IEV_NEXT_INSERTED_OBJECT (-1) which refers to the next object to be inserted or IEV_PREVIOUS_INSERTED_OBJECT (-2) for the last object inserted.