Is it possible to validate field based on it's sibling value?

[Ketler13]

Let's say I have a !group or !struct type of field (A) with couple of subfields (B, C).
Is it possible to validate subfield B based on what's selected in field C just after user input not at the export stage?
Thank you

[ukrbublik]

For now it's not possible
(at least with easy way. I mean, you could search for values of B/C by parsing the current tree and use it in fieldSettings.validateValue for field A, but it's hard)
Please open issue for a feature request