There are two ways to add breakpoints. The first is to double-click on an action statement with the left mouse button. The second is to enter a breakpoint by filename and line number in the Breakpoints dialog box

Note: Breakpoints can only be set on action statements. If an action statement extends to more than one line, the breakpoint is generally set on the first line of the action.

If you attempt to add a breakpoint at a location that is not valid, the following message appears:

"Invalid breakpoint location. Breakpoint was not set."

If you have a source view open on a file that contains breakpoints, the breakpoints appear highlighted in red.