When you add an Attribute in Class by operating in the Property View or using shortcut key "Ctrl+F", the attribute will be added in the last line. Then if you want to sort them, you have to go to the Property view and use [Up] and [Down] button to place the Attribute where you want to place it.

Since 3.0 Version, you are able to add Attributes by just pressing [Enter] key on the Diagram Editor.
It has made it very easier to insert Attributes where you want to place them because Attributes would be added right after the one you had selected when pressing [Enter] Key.

You can do the same with adding Operations.
I bet this will cut your time off going back and forth to property view and the Diagram Editor.