If checked, your horizontal line will be a shadow line. If not checked, it will be a solid line.
Align
Select the alignment you want for your horizontal line from this pop-up menu.
Thickness
Enter the vertical size (height) of your horizontal line. Note: If left blank, the line will be one pixel thick.
Select 'Percentage' to measure the size of your horizontal line as a percentage of the size of the window, or select 'Pixels' to measure the size of your horizontal line in pixels.
Width
Enter the width (length) of your horizontal line. Note: If left blank, the line will span the entire window length.