Allow specific custom fields to be mandatory whilst editing via a list

[#1]

Currently it is possible to set a custom field as mandatory but this is only enforced if the user is editing data via the custom form screen.

Some of my users would like the mandatory field to be enforced whilst editing is done via a task list / project list etc.

I suspect that this is not currently supported for performance reasons but if it were possible it would certainly be a useful feature.