I am working on complex script and it would help to see the color marks in the text view perhaps as a line above the glyph or a square in the top left of each glyph?
I order my glyphs in a certain way based on their relationship to each other, this can not be achieved using glyph list in font view as my glyphs repeat themselves due to sharing a relationship with many other glyphs (as in the case of components) and I can not display the same glyph twice in filter list.
Thank you.
Could you make a mockup on how it should look?
A thousand thanks for the plug in!!! It works and actually better than I imagine.
There is a problem when using components
see this preview http://pasteboard.co/1GWlDtNL.png those glyphs with parts are components but are not colored http://pbrd.co/1qHDSpa.
Fixed the mistake, will upload a new version in a minute.
Thank you for pointing it out, I never tested it with components. 
[EDIT:] my internet connection here does not allow the github upload, so it will take longer. In the meantime, you can fix it yourself by opening GlyphsInLabelColor.py inside the plugin, and changing line 110 from:
thisBezierPath = Layer.bezierPath()
to:
thisBezierPath = Layer.copyDecomposedLayer().bezierPath()
Make sure you keep the same indentation. Then save, and restart Glyphs.
[EDIT 2:] New version is on GitHub now.
And how about marking letters on the masters separately?
You know A on the master1 red and A on the master 2 blue,
I’m waiting for this for a long, long time, and will be more than happy with the plug in.
The plugin is ready for that and will support layer colors, should they ever appear in Glyphs. I cannot say more yet. Haha.
I don’t need more. Haha Indeed.