To add a line breakpoint, perform one of the following tasks in the editor area:
A new line breakpoint marker is displayed in both the Breakpoints view and on the marker bar (directly to the left of the line where you added the breakpoint). If a line is not valid for breakpoint-setting (such as an empty line or a comment line), selecting Toggle Breakpoint or double-clicking it does nothing.
When a breakpoint is enabled, thread execution suspends before that line of code is executed. The debugger selects the thread that has been stopped by the breakpoint and automatically displays the stack frames for that thread. The line where the breakpoint was set is highlighted in the editor.