Hide/show element based on field element empty/not empty

[jfquestiaux]

It's all in the title: is it possible to hide/show an element based on another field (plain field element) being empty or filled?
There has been some useful additions to the conditions (like "contains",...) but would it be possible to have a "NULL" or "NOT NULL" condition as well?

 

[jfquestiaux]

OK, in fact this is working fine if you use the condition "==" / "!=" and leave the last field blank.
I could not have it working before because of a JS error causes by CDD on multi page forms. I disabled those and now the hide/show works fine.