Private Declare Function TransparentBlt Lib "msimg32" _
(ByVal hdcDest As Long, _
ByVal nXOriginDest As Long, _
ByVal nYOriginDest As Long, _
ByVal nWidthDest As Long, _
ByVal nHeightDest As Long, _
ByVal hdcSrc As Long, _
ByVal nXOriginSrc As Long, _
ByVal nYOriginSrc As Long, _
ByVal nWidthSrc As Long, _
ByVal nHeightSrc As Long, _
ByVal crTransparent As Long) _
As Long
 
Private Declare Function GetPixel Lib "gdi32" _
(ByVal hdc As Long, _
ByVal x As Long, _
ByVal y As Long) _
As Long
 
Private Function fMakeTransparentRegion(pbSource As PictureBox, _
        pbDestination As PictureBox)
Dim lTransColor As Long
 
lTransColor = GetPixel(pbSource.hdc, 0, 0)
Call TransparentBlt(pbDestination.hdc, 0, 0, pbSource.ScaleWidth, _
            pbSource.ScaleHeight, _
            pbSource.hdc, 0, 0, _
            pbSource.ScaleWidth, _
            pbSource.ScaleHeight, _
            lTransColor)
    Picture2.Refresh
End Function
 
Private Sub Command1_Click()
    fMakeTransparentRegion Picture1, Picture2 
End Sub
 
Private Sub Form_Load()
 Picture1.Picture = LoadPicture(App.Path & "\3DSmiley16.bmp")
    With Picture1
        .AutoRedraw = True
        .ScaleMode = 3
        With Picture2
            .AutoRedraw = True
            .ScaleMode = 3
            .Width = Picture1.Width
            .Height = Picture1.Height
        End With
    End With
End Sub