This video explains how the "Behavior Creation Mode" button within Cameo Enterprise Architecture, Cameo Systems Modeler, and MagicDraw.
We will remember that SysML has the following syntax:
"element of usage : element of definition"
so on an Activity diagram the syntax will be
"action : activity"
The "Behavior Creation Mode" button allows for users to toggle whether the activity is created along with the action. If toggled "On", the creation of a an action will automatically create and activity, if toggled "Off", the creation of an action will not create an activity.
Most of the time itis easier to model with this functionality set to "Off".