LineFormat.BackColor (Word)

Returns or sets a ColorFormat object that represents the background color for a patterned line.

Dim docActive As Document 
 
Set docActive = ActiveDocument 
 
With docActive.Shapes.AddLine(10, 100, 250, 0).Line 
 .Weight = 6 
 .ForeColor.RGB = RGB(0, 0, 255) 
 .BackColor.RGB = RGB(128, 0, 0) 
 .Pattern = msoPatternDarkDownwardDiagonal 
End With