I've written an Excel application that has extensive use of macros,
graphics,... During testing, somebody managed to open the thing in
design mode (not open then shift to, but actually opened in design
mode) She was a novice Excel user and didn't even recognize it.

I managed to design-in a warning to enable macros (trick: Save the
thing with a warning screen displayed then have a macro associated with
opening the workbook take it to the 'real' startup. That only works if
macros are enabled and is just a quick flash for those who have them
enabled. Everyone else just gets that warning screen) so the buttons
with their associated macros work. But when you are in design mode
sliders don't work and I use sliders, too. How can I tell if the sheet
is opened in the "wrong" mode and shift to the "right" one?

And as an aside, she noticed that she (sometimes) didn't have various
toolbars displayed. How can I (in a macro) put ALL of them away?