Hello (Andrea),
There is an error in the latest changes in the FlatNotebook.
Line 1280:
c = wx.MacThemeColour(Carbon.Appearance.kThemeBrushFocusHighlight)
There is no wx.MacThemeColour method on the 2.8 Branch, it only exists on the 2.9 branch. After reviewing the history files I am guessing you may have made your latest changes on the 2.9 branch and then just copied the file over to the 2.8 branch. As the changes to use wx.MacThemeColour on the 2.9 branch appear to have been made by Robin in r50627.
Suggest simply reverting to a slightly modified version of the previous code on the 2.8 branch.
brush = wx.Brush(wx.BLACK)
brush.MacSetTheme(Carbon.Appearance.kThemeBrushFocusHighlight)
self._focusPen = wx.Pen(brush.GetColour(), 2, wx.SOLID)
The 2.9 branch version can stay as is since in 2.9 Brush::MacSetTheme has been removed.
Thanks,
Cody