I have branched this into a separate thread as it appears to be in a different question to the one where it was added.
I'm not clear on what you want. If you simply want a table in the dropdown, the editor allows that. It might be easier to create the content in the topic first and then cut and paste it into the dropdown. If if is something else you want, please explain.
What Peter described is pretty much the ONLY way I like to work with drop-down areas. Compose things in the topic as you want. Then select what should be in the drop-down and perform a Cut. Then open that squirrelly dialog and perform a Paste.