Shoutbox

I'm programming in VB6 and using the following code to retrieve the background color of the selected text in a RichTextBox:

code:

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Public Function GetTextBackColor(ByVal rtfBox As RichTextBox) As Long
    Dim tCF2 As CHARFORMAT2
    tCF2.dwMask = CFM_BACKCOLOR
    tCF2.cbSize = Len(tCF2)
    Call SendMessage(rtfBox.hWnd, EM_GETCHARFORMAT, ercSetFormatSelection, tCF2)
    GetTextBackColor = tCF2.crBackColor
End Function

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It works well, but when the background is not set (in that case we commonly see a white one), it returns 0; and it also returns 0 for a black background. So how can I make the difference between the two?

Please help me!