The following double click shortcuts are added to the class diagram.
The menu options shown in the red circle below are installed with the extension and will show when you click on the appropriate elements in the class diagram. These options allow for quick class creation with association links. The menu options will be disabled if you have not clicked on the required number of elements.
The disabled options for creating associations are not enabled in the screenshot since I've only clicked on one element. If two elements are selected, then the Create Class... options will be disabled and the Create Asscoation... options will be enabled. Here's a reference chart that describes what each Create Class option should be used for.