To set a breakpoint from the Stepper, position the cursor where you want the breakpoint and choose
Debug > Stepper > Breakpoint
or click 
in the Stepper toolbar.
Figure 23.4 A breakpoint on the function call
+
When you step though code, or choose Debug > Stepper > Continue , when a breakpoint is reached execution stops and the breakpoint is displayed.
To set a breakpoint from the Editor, see Breakpoints.