BLT is a very powerful extension to Tk. It adds plotting widgets
(graph, barchart and stripchart), hierarchy tree and table, tab
notebook, table geometry manager, vector, background program
execution, busy utility, eps canvas item, drag and drop facility,
bitmap command and miscellaneous commands.
Note: this version is stubs enabled and therefore should be compatible
with Tcl/Tk versions after and including 8.3.1.
