Variable: left-margin-width

left-margin-width is a buffer-local variable defined in buffer.c.

Documentation

Width in columns of left marginal area for display of a buffer.

A value of nil means no marginal area.

Setting this variable does not take effect until a new buffer is displayed in a window. To make the change take effect, call set-window-buffer.

Probably introduced at or before Emacs version 21.1.

Source Code

// Defined in /usr/src/emacs/src/buffer.c
  DEFVAR_PER_BUFFER ("left-margin-width", &BVAR (current_buffer, left_margin_cols),
		     Qintegerp,
		     doc: /* Width in columns of left marginal area for display of a buffer.
A value of nil means no marginal area.

Setting this variable does not take effect until a new buffer is displayed
in a window.  To make the change take effect, call `set-window-buffer'.  */);