Creating Checkboxes that when click uncheck the other

[LarryG]

If I can intrude on the thread to ask some questions about the posts here, here they are; but I'll edit them away and put in another thread if asked:

I've always wondered how Excel knows whose option buttons are whose, but out of habit I've always just drawn a frame around them (or dragged them into a frame, actually). Is a GroupBox something different? [Disclaimer: the scope of my knowledge is what appears in the form Toolbox.] Anyway, I just tested a blank form with 1 option button, copied it twice, hit F5, and the three worked in concert (correctly) without anything to "group" them except the form boundary itself.

One more thing, is invisibility advantageous for the frame or Groupbox? It would seem easier to keep things straight if visible. I guess since it's visible in design, and can't be clicked on or tabbed to at runtime, it's not problematic; just wondering why you would though. (And I've actually deliberately made a invisible/transparent control before myself - as a trick to do a flyover message when moused over.)

And by the way, this whole discussion is about UserForm controls, rather than controls directly on a worksheet, right? If not, maybe ignore all my scribbling!

EDIT: I just drew a frame and dragged them in, but now I can't cycle around with the tab key. I can tab from button 1 to button 2 to button 3, but it stops there. Was I just wrong to use a frame at all?!