Form Guides are designed to execute your form in a Flash environment and mirror what is done in the PDF because you might decide to deploy a form as a Form Guide without the PDF behind it. The catch is that Form Guides (and HTML forms) operate on the XFA Subset which means that you don’t have access to all the APIs which you can access when your script executes in Acrobat/Reader.

If you need to write scripts that use more than the subset in order to do special things only in the PDF, you need to “protect” that code with a check to ensure it executes only in the context of the PDF. You can do this by checking the value of the xfa.host.name property. If it’s “Flash”, then your in the context of the Form Guide. Otherwise, you’re in the PDF:

if (xfa.host.name != "Flash")
{
    // do the PDF-only/full-XFA stuff...
}

I was wondereing if you can help me on this (it´s about form guides, but not directly related with this scenario).
Before using form guides, and because I knew that I could have a pdf inside it and formguide would make a mapping of value fileds into it, I thought I could use formguides to fill-in the form and execute any normal java script inside the form at the same time.

However, it seems that the script will run inside the flash context. For instance, if I have a replace javascript function inside a change filed event, when I had a value to that field in a formguide, the change event will be fired. However, the replace function will throw an error. What functions can we use?
Another example, if I have a floating field in a pdf, the form guide will do the mapping of the vlaue to the field, however, if I do a xfa.layout,.relayout, formguide will throw an error. BUT the floating field will actually work… Why I get such behavior? If this actually work in the PDF (making a preview from formguide) why we get this error?

thank you

Unfortunately not. There just isn’t enough font information available via APIs at your disposal in order to compute the correct character width on a per-character basis for a particular font, which is basically what the algorithm would need to do.