How to populate a dropdown(select) with information from another tab of the same dialog

Hi all,

I came across with this challenge. In a touch ui dialog that is displayed after I click to "View Properties" of a page, I have a Tab A, where I should fill out some information using Text Fields, then, I need to use that information to populate a dropdown located in Tab B (of the same dialog)¿How can I do that?

I can create a servlet that search for the fields that I have filled out in Tab A and then point out the datasource of dropdown in Tab B to that servlet, however, ¿How can I choose inside the servlet the current page? I mean, every page have a dialog to configure its properties and each dropdown of each page should be filled out using its own information in Tab A.

Regards.