A breakpoint is a point marking a line of code in which you wish to have the debugger pause. It is seen as a little red dot on the left margin of the code. Like this:

This is what it looks like when the code is not executing.

Once the code begins to execute and the breakpoint is reached, the program pointer is displayed at the line in which the breakpoint is placed:

The yellow arrow over the red dot merely marks the program pointer; a breakpoint is always marked by a red dot.

Where a Breakpoint May Be Placed

A breakpoint may be placed only on a line which contains executable code; before compiling your project, you could place breakpoints anywhere. However, on compile, these breakpoints will be shifted to the nearest lines following them which contain executable code.

You could add breakpoints to your code at any time -- even while the code is running. However, while the code is running, you may only add breakpoints next to lines which contain executable code. If you click next to a line which does not contain executable code, the closest line following this line which does contain executable code will get a breakpoint.

You may have up to 16 breakpoints in your entire project. Breakpoints are saved when the project is saved.

Toggling Breakpoints

Breakpoints may be toggled (set/cleared) by putting the cursor in the line in which you wish to place (or remove) the breakpoint and pressing F9 or selecting Debug > Toggle Breakpoint. Alternatively, you may also toggle a breakpoint by clicking on the margin of the code at the point in which you wish to have a breakpoint.

You may remove all breakpoints from an entire project (including any files which are not currently open) by selecting Debug > Remove All Breakpoints.