Referencing the current dialog

In order to reference the current dialog, you can define a variable with the ui.Dialog type, and get the current dialog object with the ui.Dialog.getCurrent() method:

DEFINE d ui.Dialog

INPUT BY NAME ...
   BEFORE DIALOG
      LET d = ui.Dialog.getCurrent()
      CALL d.setActionActive("zoom", FALSE)
   ...

As an alternative and to simplify programming, you should use the DIALOG keyword in the context of the interactive instruction block. the DIALOG keyword is a predefined object variable referencing the current dialog. The DIALOG variable can only be used inside the interactive instruction block:

INPUT BY NAME custid, custname 
  ON ACTION disable 
    CALL DIALOG.setFieldActive("custid", FALSE)
END INPUT