Und noch etwas verbessert aber es tut sich immer noch nichts

Private Sub Document_ContentControlOnExit(ByVal ContentControl As ContentControl, Cancel As Boolean)
With ActiveDocument.ContentControls
    If Title = "BackgroundColor" Then
    Select Case ActiveDocument.DropdownListEntries.Value
        Case Is = "Blue"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(200, 200, 200)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case "Green"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(100, 100, 100)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case "Orange"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(100, 100, 100)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case "Yellow"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(100, 100, 100)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case "Purple"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(100, 100, 100)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case "White"
            ActiveDocument.ActiveWindow.View.DisplayBackgrounds = True
            ActiveDocument.Background.Fill.ForeColor.RGB = RGB(100, 100, 100)
            ActiveDocument.Background.Fill.Transparency = 0#
        Case Else
    End Select
    End If
End With
End Sub