onchange event on select widget (Bonita Community 6.2.3)

Hi,

Using Bonita BPM Community 6.2.3.

I'm trying to use onchange HTML event on a select widget. In the HTML attributes' widget section I write: onchange="window.alert('hello world')". But in the portal, when I run the process, the onchange attribute is gone. Strangely, if I replace onchange with onclick I get the correct HTML code in the portal (including onclick attribute).

Is this the "normal" behavior or is something wrong with my code?

Thanks, pet