How to execute a behaviour only when an option of the mapped field is clicked

[gabe vid]

Hi,

I've setup a behavior mapped to a field named "quarter".

Depending on the quarter, a duedate is prefilled:

q1 -> june

q1 -> sept

q3 -> dec

q4 -> mar

Once running, it works ok on create screen cause as I select the quarter, the duedate gets filled automatically and I can still change the date as I want if needed.

The problem arises in the edit screen: in this screen, if the date was custom written, the behavior simply ignores that and overwrites it immediately with the automatic date according to the quarter chosen previously in the create screen.

This way I can lose the duedate without even noticing.

I know I can detect the screen whether it's the create or the edit one with below code, but how can I solve my problem ?

if (actionForm.contains("Create Issue") || actionForm.contains("Create") ) {
}

Is it possible to detect when the user actually choose a quarter (either a different one or the same that was chosen in the create screen) and in that case let the behavior assign the automatic value to the duedate ?