Binaryworld - Create TextBox with dithered background ... [ VB -> Forms & Controls ]

If your video display has 256 colors or less and you assign a dithered color to the BackColor property of a TextBox control, you'll find that the background color under the text inside the TextBox is displayed in a different (solid) color.

To work around this issue, you must trap the WM_CTLCOLOREDIT message, that the control sends to its parent form when its background is about to be redrawn, and you must explicitly set a transparent background for the control. Here's the code that does the job:

Click here to copy the following block

' REQUIRES THE MSGHOOK.DLL COMPONENT

Private Declare Function SetBkMode Lib "gdi32" (ByVal hdc As Long, _
  ByVal nBkMode As Long) As Long

Const WM_CTLCOLOREDIT = &H133
Const TRANSPARENT = 1

Dim WithEvents FormHook As MsgHook
Dim TextHWnd As Long

Private Sub Form_Load()
  Set FormHook = New MsgHook
  FormHook.StartSubclass Me
  TextHWnd = Text1.hWnd
End Sub

Private Sub FormHook_BeforeMessage(uMsg As Long, wParam As Long, lParam As Long, _
  retValue As Long, Cancel As Boolean)
  If uMsg = WM_CTLCOLOREDIT And lParam = TextHWnd Then
    SetBkMode wParam, TRANSPARENT
  End If
End Sub