For text documents containing Input fields

After doing 
Insert > Fields > Other > Functions tab > Input field,
it is not obvious that the 'Reference' box may need to
be filled in to provide a prompt for the user,
before clicking the Insert button at the bottom
of the dialog.

If the Insert button is pressed first, before
typing in a prompt, the Edit dialog pops up
with two edit fields, but only the lower one
can be edited.  The upper one is empty but
cannot be edited.

It might be clearer if there were some explanatory
text saying 'Enter Prompt text in the box below
and then click the Insert button'.

Both in this dialog and in the 'Edit Fields: Functions'
dialog box, the label 'Reference' is confusing.
A better label might be 'Prompt Text' or
'Enter Prompt Text' or 'Enter Prompt Label'.