That's always been one of my goals as a longtime professional writer, to use it as many times as I could. Celtx's Adapt feature does exactly that. You can, with one click, change formatting on your screenplay to a stage play or a comic book or any of the other formats which Celtx knows (and you can add additional formats as needed). That's pretty powerful.

Okay, I decide "Portals" would make a good comic also. To convert or adapt (in Celtx parlance), click on Script (top menu, see the following screenshot) and then select Adapt To. Then choose Comic Book:

Do a Save As and we have "Portals" now as both a Film project and a Comic Book project. I'll need to go through and add balloon types and a few other things, but everything is already in the correct industry standard comic book format.