Creates a small separating gap between elements. This type of separator should be used to separate parts of a dialog. It doesn't draw a bar visually, but is just a small space. It is functionally equivalent to a
spacer except it defaults to a small size (usually 1.5 ems).
is a horizontal or vertical separator. Note that the values are the reverse of what seems more likely.
Inherited from XUL element
The following classes may be used to style the element. These classes should be used instead of changing the style of the element directly since they will fit more naturally with the user's selected theme.