How Can I Save A Class Diagram In Intellij?

I discovered that in Intellij I can create nice class diagrams by going to New > Diagram > Java Class Diagram. I can do everything that I want to do, except figure out how to save the diagram after I'm done. When I create a diagram, save it, shut down Intellij, and then start it up again, I see that the diagram that I had just "saved" has reverted to a generic window displaying all of the packages in my project. I realize that I can save the diagam in a PNG format, but I don't want to do that. I want to be able to save it in an editable format? Thoughts?

Solution

The top left save disk does nothing. The right save disk will actually save the diagram.

Screen shot showing which save disk to click