Keyword Test - Get new Id value from textbox

I apologize ahead of time in case the answer to my question should be obvious.  I have not been able to find it.

I want to run a desktop app that creates a new widget.  Once the widget is saved, the new Id appears in a textbox.  I want to get the Id from this textbox and save it in a csv file to use as input to another test.

Recording the test works great.  How do I hook to the textbox, get the value from it, and write it to a file?