P: SDK: LrDialogs.presentModalDialog - actionBinding is broken

LrDialogs.presentModalDialog - actionVerb works fine, but actionBinding is ignored.

for example, if I write:

local args = {}


            args.actionVerb = "Test"


            args.actionBinding = 'test'


            accItems[#accItems + 1] = 


                vf:push_button {


                    title = str:fmt( "Doesntmatter" ),


                    action = function( button )


                        LrDialogs.stopModalWithResult( button, 'whocares' )


                    end


                }


        end


        args.contents = vf:column( mainItems ) - main-items not relevant.


        args.accessoryView = vf:row( accItems )


        args.save_frame = 'testPrompt'

local answer = LrDialogs.presentModalDialog( args )

then click the 'Test' button, the value returned in answer will be 'ok' - I expect it to be 'test'.

Is it broken? or am I using it incorrectly???