How to colour a field red?

[peterraeves]

When a field is mandatory but not filled in, the label blinks for 2 seconds and the field becomes red. I want to replicate this behaviour. I found that g_form.flash does the former, now how would I be able to do the latter?

[Prasun]

Peter, Did I understand this time or again I got it wrong?

A snapshot will be helpful what you are trying to achieve.

[peterraeves]

You can easily replicate this on your instance.

1. Keep a mandatory field empty

2. Save

3. See what happens to the field

I want to do what happens there, without having to make the field mandatory, because I want this behaviour only for certain values, instead of the empty value.