The Diagram mode graphically displays the Web flow of the application defined in the Struts configuration file.
The Diagram mode allows to edit navigation in your Struts application. Just by right-clicking anywhere on the diagram, you can use a context menu to create the building blocks of a Struts application:
Actions
Global forwards
Global exceptions
JSP Pages
Along the upper-left side of the editor is a stack of seven icons for changing the behavior of the cursor in the diagram.
The first icon switches to the default regular selection cursor, the second to the marquee selection cursor and the third to the new connection cursor. The last four icons switch the cursor to an insert cursor for each type of Struts build block listed above (and in the order listed).
For instance, clicking on the first of these four icons (the one with the gears) will switch the cursor to insert actions. Clicking anywhere in the diagram with this cursor has the same effect as right-click and selecting Add > Action... from the context menu with the regular cursor active. It's just more efficient to use this cursor if you're adding more than one action at once.