This callback takes ScriptDialog with the details of what dialog you need to display to the user. When window.prompt("A","B") the even fires and we can get at the two input strings (using scriptDialogGetMessage and scriptDialogPromptGetDefaultText), but the function for specifying the return value scriptDialogPromptSetText does not seem to work.

I suspect the problem might be that the ScriptDialog object is being copied and the one we are modifying is not the one that was passed to the signal. Is that possible?