JIra gadget wrtie UserPref programmatically?

Hi,

I’ve declared a user pref in a gadget

<UserPref name="mypref" datatype="hidden" default_value="" />

Everything works fine since I can edit it, set some value and read it with

gadget.getPref("mypref")

My question:
Is it possible to change its value programmatically?

A sort of

gadget.setPref("mypref", "somevalue")

It looks like it is possible with

var prefs = new gadgets.Prefs();

but I’m unable to make it work:

prefs.set("mypref", "somevalue")
prefs.setString("mypref", "somevalue")

etc.

Nothing seems to work.

Any help would be very appreciated.

Thanks,
Pablo