Add personal comments to a graph?

Sometimes I would like to add some personal comments to each graph. "Add Annotation" does not suit this purpose since I want the comments invisible when the graph is saved as an image file for manuscript use. Creating a Notebook window to write comments on works for the purpose, but is not as convenient and neat as attaching the comment right next to the original graph. I wonder if there is a way to attach notes to a graph and is visible only in Igor Pro (i.e., become invisible when saved as an image file)?

P.S. For now I have been adding short comments in the Window Title for this purpose, but sometimes I need to put longer comments.