flowchart demo: because other vendors already do!
You should include a flowchart demo for your diagram tool. It is possible - somewhat - but you are not even including a demo for it, while vendors like syncfusion do!
The way I found out a flowchart was possible was because of the Kendo UI cookbook and cookbook code files.
Seriously, I don't know why you are not including a demo for a flowchart in your demo list for the diagram tool; this should be a no-brainer to include, and in theory, you should not even have to build anything new, just use the diagram tool you have already made.