Create UI parts using the diagram editor
From the documentation (https://doorsng602b.clm.ibmcloud.com/clmhelp/index.jsp?re=1&topic=/com.ibm.rational.rrm.help.doc/topics/c_diagram.html&scope=null):
You can now create parts using the new diagram editor
But there is no such feature! I can't find option like "Save selection as user interface part". Should I use the browser extension for UI Sketching?