Subroutine ShadeForm begins by setting the form's background color to the color that should be displayed on the outside edge of the gradient. It then draws a series of concentric ellipses starting with the outer ones and moving in. Each is filled with the next color in the gradient.

' Fill the form with an elliptical gradient.
Private Sub ShadeForm()
Const COLOR_OUTER = 64
Const COLOR_INNER = 255

Dim cx As Single
Dim cy As Single
Dim r As Single
Dim i As Single
Dim clr As Single
Dim dclr As Single

    Cls
    ScaleMode = vbPixels
    cx = ScaleWidth / 2
    cy = ScaleHeight / 2
    BackColor = RGB(0, 0, COLOR_OUTER)

    If cx > cy Then
        r = cx
    Else
        r = cy
    End If
    FillStyle = vbFSSolid
    DrawStyle = vbTransparent
    dclr = (COLOR_INNER - COLOR_OUTER) / r
    clr = COLOR_OUTER
    For i = r To 1 Step -1
        FillColor = RGB(0, 0, clr)
        ForeColor = RGB(0, 0, clr)
        clr = clr + dclr
        Circle (cx, cy), i, , , , cy / cx
    Next i
End Sub