TopDraw is a sketchpad for drawing topology cartoons of proteins
written in Tcl/Tk. It does not calculate topology from a PDB file, but
merely allows you to sketch a topology derived from another source.

Features:
- Easy sketching of protein topologies
- Save/Open function for reusing/editing previous drawings
- Postscript output for printing/publication
- Horizontal or vertical helices and strands
- New version allows diagonal connections

Note: The source is not versioned, so a MD5SUM missmatch is expected
when upstream released a new version.

Reference:
TopDraw: a sketchpad for protein structure topology cartoons. Bond CS.
Bioinformatics. 2003 Jan 22;19(2):311-2.