vprerex 1:6.5.1-1build1 (amd64 binary) in ubuntu focal

 vprerex provides a Qt interface to prerex by integrating the prerex editor
 with a PDF viewer. This allows conveying coordinates of course boxes, arrows
 and background points back to prerex through the use of the clipboard.
 .
 prerex is an editor for creating esthetically pleasing course prerequisite
 charts using the TikZ LaTeX package.
 .
 Course prerequisite charts allow students to easily determine which
 prerequisites, corequisites and recommended prerequisites they need for a
 given course and their time slots. Course prerequisite charts also highlight
 the courses required by a degree.
 .
 prerex is used by departments in several universities, including Queen's
 University and Suffolk University.