The BackColor property returns or specifies the background color in a two-color bitmap pattern fill.
Examples:
The following VBA example creates a rectangle, applies a two-color bitmap pattern to it, and changes the background color to red.
Sub Test()
Dim s As Shape
Dim pf As PatternFill
Set s = ActiveLayer.CreateRectangle(0, 0, 2, 2)
Set pf = s.Fill.ApplyPatternFill(cdrTwoColorPattern, , 6)
pf.BackColor.RGBAssign 255, 0, 0
End Sub