Help with PHAB

How can I block a dialog module so the user can´t go to other window until clicks Ok button?

If you just want to put a message on the screen that the user has to confirm use PtNotice() or PtAlert() and set the Pt_MODAL flag.

If you want to use your own dialog module as a modal dialog have a look at functions like PtBlockAllWindows().
There is a section with functions for modal dialogs in the helpfiles (just search for “modal”).

Thanks for your help!
Another question: How can I know wich item is selected in a PtList?
I tried with Pt_ARG_ITEMS and Pt_ARG_SELECTED_INDEXES, but I can´t figure out.