I did kind of a workaround for this issue in my latest release of Form Wizard Pro (as seen on demo.mojoportal.com). When I made the instruction block question type so that additional instructions could be added anywhere among the questions, I wanted to allow the user to be able to use html editor to edit the instructions, but it was inside updatepanel and this did not work. So my solution was to use a GreyBoxDialog and popup the editor in a new window, and then I used a callback javascript from the dialog to refresh the the update panel after editing is complete so it would reload the data saved separately from the dialog page.
So that is another solution that can be used, but I have a feeling this editor in the toolkit will come in very handy.
Best,
Joe