pyRevit VS RevitLookup

I've just checked the API and yep, it is possible, with limited functionality. And to also add some value to the thread: https://github.com/eirannejad/pyRevit can also do this, for free!

This is a topic that has been covered in much detail by the Revit community. Jeremy Tammik has several examples covered in such detail on his website the building coder and you can search modeless dialogs in the search bar. The way I found some examples was simply by googling how to make modeless windows in Revit. There are tons of resources and a lot can be found just by googling, searching other peoples code, and the Autodesk Revit API forums. The funny thing is I was trying to understand this before I got the error and was having trouble grasping the concept. My plugin was working just fine but I was not making any transactions yet. Finally once I got to the point in making a transaction, I received the error and it made much more sense on what needed to be done once I received the exception. Anyways, keep truckin and cheers!

You’ll definitely want RevitLookup installed as well so you can explore the API live in Revit. https://github.com/jeremytammik/RevitLookup

The "Insert from File" command opens up the Revit model you are copying from in the background, and then just doesn't bother to close the Revit model when the command ends. You can use the Revit Lookup tool to snoop the Revit application and see in the Revit model is still open in the background. I have no idea why they haven't fixed this bug after soo many years. If I remember correctly if someone else uses the worksharing monitor in the Revit model you are trying to copy from, it shows you as having the Central model open, not a local copy of it.