dropdown.settings.onceDropDown element

getDropDown(id).settings.once() (since PennController 1.5)

Will disable the DropDown element after selection occurs.

Example:

newText("I saw Erika talk to Nate.")
    .settings.after( newDropDown("").settings.add("He","She").settings.once() )
    .settings.after( newText("seemed anxious.") )
    .print()

Prints I saw Erika talk to Nate. ___ seemed nervous onto the page, where ___ is a drop-down list containing the options He and She. The command .settings.once makes the selection of He or She definitive.