at the moment i have no time to produce a full, working Tk example but you have a lot of possibilities. First of them you can create so called hyperlink (as in
example) and modify the sub to spawn another windows where the file content is showed. see
for an example.
You can also, if nasty, make a system call to open the editor of choice with the path as argoument.
There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.