HTML popups ?

Hello all,

I have the need for a generic popup window in which I can place random HTML
stuff.  The thing is that I want to be able to dismiss the popup as any
other popup : by clicking outside of it.

The problem with that is that I can't get such a thing to happen on, for
example, a simple DIV.   A statically set "onblur" and others won't fire,
and when I add them dynamically they fire as soon as they are set.

The only thing that I got to work as a popup is a (unfolded) SELECT (which
can receive focus) - but that one isn't really flexible.

And alas, my bout of googeling didn't give me anything in the above
direction either (lots of hints, but nothing that lead to a working
solution).

In short : does anyone here know, and wants to share, what to use for such a
popup window ?

Almost forgot : my current browser is FF 52.

Regards,
Rudy Wieser