It would be really nice if you could add multiple attributes or operations by typing them onto the diagram. maybe ctrl-enter to go to the next one.
currently the easiest way is from the specification dialog, but even there you have to click on “add” each time.
also I find it odd that the context menu for the class has “add->attribute” at the top, and the context menu for class members has “new attribute” at the bottom. its not consistent.