The Inline Activity Chooser allows you to show and hide activities within the Process explorer.
Click on the 
icon to open a drop-down menu, listing all available activities:
Choose the activities that you wish to display in your process graph. All deselected activities will be hidden in the graph.
As a help, you can use the search field or the small icons next to the field, to find and select your cases:
will select all available cases.
will deselect all selected cases.
Don't forget to confirm with 
.