Attribute editing: value relation widget (multiple selection)

[leolami]

Checklist

• I've searched through the existing issues and this bug has never been reported before

Subject of the issue

Manage options:

• allow multiple selection
• number of columns (?)

Steps to reproduce

Example in QGIS

Environment

v3.9

Link to your project

No response

Additional info

No response

[volterra79]

@leolami @wlorenzetti we need to take in account the response of QGIS server as below:

[volterra79]

@leolami parliamo se ha senso costruire un altro tipo di input con i cleckbox selezionabile (vedi numero colonne) o lasciare la possibilità di selezione multipla e basta