+@node Source Buffers
+@subsubsection Source Buffers
+@cindex GDB commands in Fringe
+
+@c @findex gdb-mouse-set-clear-breakpoint
+@c @findex gdb-mouse-toggle-breakpoint
+Many GDB commands can be entered using keybindings or the tool bar but
+sometimes it is quicker to use the fringe. These commands either
+manipulate breakpoints or control program execution. When there is no
+fringe, you can use the margin but this is only present when the
+source file already has a breakpoint.
+
+You can click @kbd{Mouse-1} in the fringe or display margin of a
+source buffer to set a breakpoint there and, on a graphical display, a
+red bullet will appear on that line. If a breakpoint already exists
+on that line, the same click will remove it. You can also enable or
+disable a breakpoint by clicking @kbd{C-Mouse-1} on the bullet.
+
+A solid arrow in the left fringe of a source buffer indicates the line
+of the innermost frame where the debugged program has stopped. A
+hollow arrow indicates the current execution line of higher level
+frames.
+
+If you drag the arrow in the fringe with @kbd{Mouse-1}
+(@code{gdb-mouse-until}), execution will continue to the line where
+you release the button, provided it is still in the same frame.
+Alternatively, you can click @kbd{Mouse-3} at some point in the fringe
+of this buffer and execution will advance to there. A similar command
+(@code{gdb-mouse-jump}) allows you to jump to a source line without
+executing the intermediate lines by clicking @kbd{C-Mouse-3}. This
+command allows you to go backwards which can be useful for running
+through code that has already executed, in order to examine its
+execution in more detail.
+
+@table @kbd
+@item Mouse-1
+Set or clear a breakpoint.
+
+@item C-Mouse-1
+Enable or disable a breakpoint.
+
+@item Mouse-3
+Continue execution to here.
+
+@item C-Mouse-3
+Jump to here.
+@end table
+
+If the variable @code{gdb-find-source-frame} is non-@code{nil} and
+execution stops in a frame for which there is no source code e.g after
+an interrupt, then Emacs finds and displays the first frame further up
+stack for which there is source. If it is @code{nil} then the source
+buffer continues to display the last frame which maybe more useful,
+for example, when re-setting a breakpoint.
+