For example, you can drag a Class element from the Model Browser to the Type property in the Operation Specification window. That Class element is assigned as the Operation type in the Specification window.
In both cases, an association is drawn from the classifierto a property's type. The property itself is set as an association end. If the classifier symbol is not present on the diagram, it is added as a result of the created association.
If selected model elements are not compatible with an open diagram, you will not be allowed to drag these model elements.
Dragging in diagrams
You can drag-and-drop relationships to a diagram. The path for the relationship with shapes at the end of the path and the path between the shapes (if shapes at the end of the path are already represented on the diagram) is created.
You can also drag-and-drop model elements to a note or a text box symbol in a diagram to add a hyperlink to that element.
Drag a Property, Actor, Class or Instance Specification to an Activity diagram by using the right mouse button. From the shortcut menu, select to create a Swimlane, Central Buffer Node, or available Actions.