Thank you for your work, I like it a lot!
I have found two issues:
If I insert an unp-Control to a xPage, there are no custom properties visible (this is equal for all the controls I have tried), but the properties can be filled directly in the source code of the xpage. I am using Domino Designer Client 9.0.1.
If I use the unpFormviewer, there is no custom property "closexpagename" available. If I take a look into the documentation on github, there should be a property like this.
Could you take a look at this issues? Thank you from Hamburg
Kay