It would be nice to be able to grab a tab in Geany, pull it off the window, thus creating a second Geany instance holding that document.
You could also drag tabs from one instance to another, effectly closing the document in the first instance and opening it in the second.
This behavior is common in web browsers such as Firefox and Chrome and chat programs such as Pidgin and Empathy.
I understand it might be tricky if there are unsaved changes (since its not as simple as close/re-open). But if thats a problem it could be allowed just for saved documents. Or optimally the unsaved changes could be carried over as well.
I am using a (slightly) modified version of Geany 0.18 on Ubuntu 9.10