I'm making some progress, (and learning more about plugins), by taking apart the built-in Tweak ePub plugin. This is making sense but has rasied another question:
There is a line of code:
Code:
from calibre.gui2.dialogs.tweak_epub_ui import Ui_Dialog
but there is no such file as tweak_epub_ui.py. However there is a tweak_epub.ui. Is this what actually gets used? The contents of this .ui file appear to be some sort of dialogue definition in xml.