How do I insert a screen dump into a message in the forum?

Ok, a little additional update.

It seems like it might have something to do with the little "icon" in the lower right hand corner of the text box -

I don't know what this is supposed to do, but suddenly mu toolbar was gone again, and then I tried to double-click when I got the little double-arrow when hovering over the icon. Apparently that made to toolbar to appear. It doesn't seems to work the other way around though, so I can remove the toolbar when clicking on the icon so right now I can't really test if this is the simple solution. But maybe someone knows that the purpose is of this little icon/feature?

/Steen