From this dialog the properties of the horizontal rule can be modified.
Width
The width of the horizontal rule can be selected in pixels or in percent of the available space, the default width.
Height
The height of the horizontal rule can be set in pixels.
Background
A background color can be selected by clicking on the square. This will bring up the Color Picker.
Border
A border color can be selected by clicking on the square. This will bring up the Color Picker. The size of the border can also be selected in pixels.
