 (defun rdebug-secondary-buffer-populate-map (map &optional menu)
   (define-key map "B" 'rdebug-display-breakpoints-buffer)
   (define-key map "C" 'rdebug-display-cmd-buffer)
+  (define-key map "d" 'gud-down)
   (define-key map "D" 'rdebug-display-display-buffer)
   (define-key map "O" 'rdebug-display-output-buffer)
+  (define-key map "s" 'gud-source-resync)
+  (define-key map "S" 'rdebug-display-stack-buffer)
+  (define-key map "u" 'gud-up)
   (define-key map "V" 'rdebug-display-variables-buffer)
-  (define-key map "S" 'rdebug-display-stack-buffer)
   (define-key map "?" 'rdebug-display-secondary-window-help-buffer))
 
 (defun rdebug-display-breakpoints-buffer ()

 B - Breakpoints buffer.
 C - Command buffer (the debugger shell)
 D - Display buffer (also known as Watch buffer)
 O - Output window
 V - Variables buffer
 S - Stack trace buffer
 ? - This help text.
"))))

	     "Step one line (skip functions).")
    (gud-def gud-print  "p %e"        "\C-p"
	     "Evaluate Ruby expression at point.")
    (gud-def gud-source-resync "up 0" "\C-l"
	     "Show current source window")
    (gud-def gud-remove "clear %d%f:%l" "\C-d"
	     "Remove breakpoint at current line")
    (gud-def gud-run    "run"       "R"
