CSHARP

Transparent UserControl

Protected Overrides ReadOnly Property CreateParams() As CreateParams
    Get
        ' Make background transparent
        Dim cp As CreateParams = MyBase.CreateParams
        cp.ExStyle = cp.ExStyle Or &H20
        Return cp
    End Get
End Property

Protected Overrides Sub OnPaintBackground(e As PaintEventArgs)
    '' call MyBase.OnPaintBackground(e) only if the backColor is not Color.Transparent
    If Me.BackColor <> Color.Transparent Then
        MyBase.OnPaintBackground(e)
    End If
End Sub

c# UserControl make background transparent

public partial class UCTransparent : UserControl
     {

         public UCTransparent()
         {
                InitializeComponent(); 
         }
         protected override CreateParams CreateParams
         {
                get
                {
                       CreateParams cp = base.CreateParams;
                       cp.ExStyle |= 0x20;
                       return cp;
                }
         }

         protected override void OnPaintBackground(PaintEventArgs e)
         {
             base.OnPaintBackground(e);
         }
      }