Triggered by here:
There is a potential fix there, but it seems the implementation of Color reference in core is broken.
In demo.globalqss.com I tried to create a new column with name Color and reference Color.
It could not be created because the type is varchar and it requires to be a foreign key to ad_color_id
So, I created the column Test.AD_Color_ID instead, with reference Color - and this worked "fine" on database, creating the column and the foreign key.
The field is displayed in Test window as a color picker, but it cannot be saved because it tries to save the Color code and the system expects and ID as a reference for the table AD_Color_ID.
Conclusion, Color reference is broken, not working at all.