I use specific folder icons in Explorer to highlight the folders I use most so they're easy to find. Is there a way to have these icon display in Ultraedit's directory tree?

I think not. It seems that the explorer in UE is a UE implementation and not an integration of the Windows explorer.

I recently sent IDM support a feature request to have the UE explorer recognize the Windows explorer setting to show/hide hidden files and folders or implement a UE explorer setting to the same effect.

If you think the possibility of changing icons is essential then send IDM Support a feature request. See e-mail at the top of this page.