When should a Willow_Draw_Tree be done? After a delete?

This is a library that provides a Tree widget for Tcl/Tk. It lays out
a tree structure of objects on a canvas.

It also provides some canvas-widgets that are useful for displaying
text.

Typically a user will have their own tree data structure for storing
data. It seems inefficent to perform the tree operations in two
places.

There should not be any equivalent of the tclsetup.c that is used the
TCA tools in the tree library.

The Tcl Functions are:

Willow_Create_Tree --> tree identifier (an integer value of a C ptr)
Willow_Insert --> identifier for the new node
Willow_Delete --> undefined return result
Willow_Draw_Tree --> returns [width, height] of the tree
Willow_Replace --> identifier for the new node

The C Functions are:

