There is a bug in the Glyphs.registerDefault() method. It always registers the string GlyphsToolHand, no matter what you specify. Paste and run this in the Macro Window:
Ohhh, I think I saw something like that recently when we struggled to get the Distance and Angle plugin working on @Frode_Helland’s machine. I don’t know exactly what happened, but I remember some wrong default entry happening. I’ll check later …
Edit
When I run @mekkablue’s lines from above, the same happens. It prints GlyphsToolHand in build 1122
@GeorgSeifert: Check the implementation of __registerDefaults__(). I think there might be a typo referencing value versus values at different spots in the method. That might be the cause of this GlyphsHandTool default issue.