The variables to control the gutter thickness, visibility status, and captioned status are all specifiers. See Specifiers.
This specifies the height of the default gutter, if it's oriented horizontally. The position of the default gutter is specified by the function
set-default-gutter-position. If the corresponding position-specific gutter thickness specifier (e.g.top-gutter-heightifdefault-gutter-positionistop) does not specify a thickness in a particular domain (a window or a frame), then the value ofdefault-gutter-heightordefault-gutter-width(depending on the gutter orientation) in that domain, if any, will be used instead.
This specifies the width of the default gutter, if it's oriented vertically. This behaves like
default-gutter-height.
Note that default-gutter-height is only used when
default-gutter-position is top or bottom, and
default-gutter-width is only used when
default-gutter-position is left or right.
Note that all of the position-specific gutter thickness specifiers have a fallback value of zero when they do not correspond to the default gutter. Therefore, you will have to set a non-zero thickness value if you want a position-specific gutter to be displayed.
This specifies whether the default gutter is visible. The position of the default gutter is specified by the function
set-default-gutter-position. If the corresponding position-specific gutter visibility specifier (e.g.top-gutter-visible-pifdefault-gutter-positionistop) does not specify a visible-p value in a particular domain (a window or a frame), then the value ofdefault-gutter-visible-pin that domain, if any, will be used instead.
default-gutter-visible-p and all of the position-specific
gutter visibility specifiers have a fallback value of true.
Internally, gutter thickness and visibility specifiers are instantiated in both window and frame domains, for different purposes. The value in the domain of a frame's selected window specifies the actual gutter thickness or visibility that you will see in that frame. The value in the domain of a frame itself specifies the gutter thickness or visibility that is used in frame geometry calculations.
Thus, for example, if you set the frame width to 80 characters and the
left gutter width for that frame to 68 pixels, then the frame will be
sized to fit 80 characters plus a 68-pixel left gutter. If you then
set the left gutter width to 0 for a particular buffer (or if that
buffer does not specify a left gutter or has a nil value specified for
left-gutter-visible-p), you will find that, when that buffer is
displayed in the selected window, the window will have a width of 86 or
87 characters – the frame is sized for a 68-pixel left gutter but the
selected window specifies that the left gutter is not visible, so it is
expanded to take up the slack.
Whether gutter buttons are captioned. This affects which glyphs from a gutter button descriptor are chosen. See Gutter Descriptor Format.
You can also reset the gutter to what it was when SXEmacs started up.