I found an UI glitch in the current Studio (not the RC).
- Go Entities and select entity.
- Switch to UNIQUE CONSTRAINS tab and define a new constraint
- Select the fields press Apply
- Switch back to the ENTITY tab and switch again to the UNIQUE CONSTRAINTS tab
- select the added constraint.
- OOPS you will not get a field selector so you cannot see the current fields in that constraint nor you can modify it.
If you close the Entity and reopen it and go to the UNIQUE CONSTRAINT TAB first, then you can see the field selector ,but if you switch off that tab and switch it again you wil lnot see the fields until you close the entity again.