re-work the "property panel"

[nicolasaunai]

• put section titles (custom and global) in bold or something that let them easily distinguished from field names
• maybe remove the UUID, the user does not care
• rename the name of the different fields so to be more straightforward what they should be used for. For instance the "global" section title is not clear what is "global" (vs "local"?). "Mandatory" is perhaps more accurate but also a bit verbose, maybe we could just put no section name for those and just name the custom section?
• could the type of the custom attribute(?) be inferred rather than asking the user to choose it? what happens if I wrongly choose string and put "2" for instance ?

[pboettch]

I'd count 2 days for that because I have the feeling there will be some discussions before during and after for this kind of ergonomic change... 2 days is conservative ;-).

[pboettch]

Needs to be discussed what really needs to be done here.

Renaming stuff and making things bold, easy.

Inferring type, well. We cannot change the type of an attribute later on (as of today), so maybe not so good idea.