I added a html resource hoping to use it in my design (simple div with some inputs).
Added it to the resources on the right but had a difficult time using it (have not figured that out yet)
Would be great if you could drag and drop the html file in resources and drop it on the design.
The only way I know how to do this, although I am not sure why you would want too, is to add a rectangle and double click it, and add the resource as an iFrame.
You can edit the innerHTML of any element. Select the element and go to Edit->Edit Element’s innerHTML…
You can then paste your div there.