ruler-mode-ruler-help-echo

ruler-mode-ruler-help-echo is a variable defined in `ruler-mode.el'.
Its value is

"S-mouse-1/3: set L/R margin, mouse-2: set goal column, C-mouse-2: show tabs"

• This variable may be risky if used as a file-local variable.

Documentation:
Help string shown when mouse is over the ruler.
`ruler-mode-show-tab-stops' is nil.