Added November 2010

Programs which present multiple XTREE controls on the screen at once require additional consideration in order to deal with the complexities of the user clicking on one XTREE control while another one has the focus. This section will attempt to cover the basic issues involved and look at some specific examples. Note that some of the principles here (particularly the subject of the next section) apply more generally to clicking between any control and XTREE (and not necessarily between multiple XTREEs).