This should explain everything.
http://blogs.msdn.com/infopath/archive/2005/01/11/350740.aspx
Brian
You have a couple of other options... you can have a custom Task Pane which accepts a password, or you can have a Modal Dialog Box which accepts a password. Both of these are standard HTML and password controls will work just fine here.

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Greg Collins [InfoPath MVP]
Please visit: http://www.InfoPathDev.com
This should explain everything.
http://blogs.msdn.com/infopath/archive/2005/01/11/350740.aspx
Brian
> Hi, can anyone explain me how can I hide a field value showing '*' instead
> chars? I have a text field where people insert a password and I would like
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>
> Gabriele Fabbri.