Like many of us, I use hidden columns in views for sorting, row coloring, etc. I also get confused sometimes when looking at the design of the view and trying to figure out which columns are hidden and which aren't.
I think it'd be very useful if the designer ...
It would be nice to have an @IsVisible function to use in Input Validation and Input Translation formulas on forms. This would make it easier to execute these functions only when the field is visible rather than using other workarounds.
Add a show when / hide when option for a tabbed table for individual tabs.
Nowadays I have to set a hide when for the whole content of the table under the tab, pretty unhandy.
It would be really useful to have an indication in the left or rignt margin when a hide when is active for a paragraph or element, so you do not have to go looking to see if one has been set.