General Caster Cast Columns v's Timeline View Group Columns

I’m using General Caster to Concatenate three columns. In General Caster, you are limited to which column type you can cast to.
Two of them are Drop-down and Long Text (not Text).
A limitation of General Caster with regard to Drop-down is, it can’t create a new label, just change to an existing one. (e.g. if the drop-down already had A, B & C as options, you couldn’t cast D, only A, B or C).
You can get around this by using the Long Text column type however, as I want to use this as a Group in the Timeline Widget, it’s useless, as you can’t group with Long Text, only Text.
This would be made far more simple if Formula columns could be used as Groupings in the Timeline View.

Thanks, Feastie.