IS_ADD_CHILD</CODE>
 and <CODE>
MSG_VIS_REMOVE</CODE>
 are the two messages used most often for tree management. When an object should be freed, it can be destroyed with <CODE>
MSG_VIS_DESTROY</CODE>
, which will remove it from the tree and then free it.</P>
<P>
<A NAME="IX_VisClass:geometry">
 </A>
Some applications will want to use the built-in geometry management features of GEOS. The geometry manager can automatically resize and reposition an entire visible object tree properly according to pre-set cons