Situation: I made the “slash” glyph, and Glyphs automatically adds it as a component to the “notequal” sign (a glyph made of the “equal” and “slash” glyphs combined). OK, great! Since I didn’t make the “equal” sign yet, Glyphs goes the extra mile and shows here an “Empty Base Glyph” symbol on top of the slash.
The only trouble is this symbol is kinda difficult to see in the Font View tab, since it’s almost black on black (very dark grey “EBG” symbol on black slash, in my case). Why not make it a different color (red maybe?) – it makes it stand out more to bring it to my attention that something is missing there. Easier to detect and fix, otherwise I might miss it and generate the font with “defective” characters.