A startup script for RoboFont that will automatically group/tabulate your fonts by info.familyName

MargielaTabs.py

from mojo.subscriber import Subscriber, registerRoboFontSubscriber
import AppKit

class MargielaTabs(Subscriber):

    def fontDocumentDidOpen(self,info):
        newFont = info["lowLevelEvents"][0]["font"]
        windowsMap = {}
        allFonts = {f.info.familyName:AllFonts().getFontsByFamilyName(f.info.familyName) for f in AllFonts()}
        for familyName,fonts in allFonts.items():
            windowsMap[familyName] = [w for w in AppKit.NSApp().orderedWindows() if hasattr(w, "windowName") and "FontWindow" in w.windowName() and w.document().font.info.familyName == familyName]
            
        windows = windowsMap.get(newFont.info.familyName)
        if windows and len(windows) > 1:
            '''
            we cant select the first one because that is the 
            newest font and it would move the other font windows.
            '''
            main = next((window for window in windows if window.document().font.path != newFont.path), -1)
            if main in windows: windows.remove(main)
            for window in windows:
                if window.document().font.path == newFont.path:
                    main.addTabbedWindow_ordered_(window, AppKit.NSWindowAbove)
		
registerRoboFontSubscriber(MargielaTabs)

@connordavenport changing line 11 to the following makes it work for Single Window Mode as well:

windowsMap[familyName] = [w for w in AppKit.NSApp().orderedWindows() if hasattr(w, "windowName") and "FontWindow" in w.windowName() and w.document().font.info.familyName == familyName]

Ahh yes yes, good point! Thanks, @colinmford!