I have a workflow variable in NINTEX Workflow 2010 with a Multiple Lines of Text field for containing the body of an email message.  When I modify the workflow to edit the content of the variable, the configure action dialog only shows a single line text box for the value.  I cannot see the whole of the text, and I cannot scroll with the arrow keys since the cursor jumps all the way to the bottom or top of the field.  I can use the mouse on the arrows in the 'scroll bar' of the box, but when I try to change something, I cannot add new line characters.

See the attachment.  There is only one line for editing the multi line value.