First of all, great work so far on this software. I rarely need to dive in to dat files but this will definitely replace Notepad++ for that purpose. The Card Helper is a great idea.
My main use for this editor will be reading f04 and f06 files. It would be great to make those files easily navigable by coloring syntax similar to the dat files.
I’d also like to see some method of auto-jumping through the files. Maybe a tree on the left where there is a one-button click to jump to OLOAD, SPCFORCE, EIGENVALUE SUMMARY, MODAL MASS, etc.