I used SetSashDClickUnsplit to switch on unsplitting for an agw.aui.AuiNotebook, but double-clicking on the sash had no effect. After some digging around in the code I found this seemed to be because my notebook pages have children so the notebook may need to look for an ancestor.
Overriding the GetTabFrameFromWindow method seems to have fixed things - I added the following at the start of the method to find the direct child of the notebook:
while wnd.GetParent() != self: wnd = wnd.GetParent()
Does this seem reasonable? I’m using wxPython 18.104.22.168 with Python 2.7 (Windows 7 and Centos 7) but the Phoenix code doesn’t appear to have changed.