Transparrent an Object

see: WinForms: How to create a control transparent to other controls

Edit: When I originally posted, I had just glanced at that code that accompanies the MS article. After looking at it, I realized that it has some implementation errors (go figure for a MS example). However, even if the coding errors are fixed, the technique used is in error. It does not paint the non-client area of obscured controls.

Here is a simplistic transparent panel control. Note that while in the designer, the panel will not be transparent. The reason for this is that because of the method used, it is difficult to edit the panel or its contents if it transparent. It may be possible to write a control designer to allow for easy editing while allowing it to be transparent, but I do not have the time right now to investigate this and I also dislike writing designers. :)

This control obtains the transparent effect by limiting the allowed region into which the control can paint. If you don't paint over it, you can see it.

Public Class TransparentPanel
   Inherits Panel

   Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
      SetPaintableRegion()
      MyBase.OnPaint(e)
   End Sub

   Private Sub SetPaintableRegion()
      ' intially set the paintable region as the entire control area
      Dim PaintableRegion As Region = New Region(New Rectangle(0, 0, Me.Width, Me.Height))

      ' if in design, do not do transparent
      If Not Me.DesignMode Then
         ' build a rectangle that represents the client area
         Dim clientrect As Rectangle = Me.ClientRectangle

         ' need to set the location of clientrect relative to Control.Location
         Dim offset As Point = ClientOriginRelativeToLocation(Me)
         clientrect.X = offset.X
         clientrect.Y = offset.Y

         ' subtract clientrect from PaintableRegion
         PaintableRegion.Xor(clientrect)

         ' now need to add in areas for child controls
         For Each c As Control In Me.Controls
            Dim r As Rectangle = c.Bounds
            r.X += offset.X
            r.Y += offset.Y
            PaintableRegion.Union(r)
         Next
      End If 'Not Me.DesignMode

      If Me.Region IsNot Nothing Then
         Me.Region.Dispose()
      Else
         Me.Region = PaintableRegion
      End If

   End Sub 'SetPaintableRegion

   Public Shared Function ClientOriginRelativeToLocation(ByVal c As Control) As Point
      Dim clientorigin As Point = c.PointToScreen(Point.Empty)
      Dim parentorigin As Point = Point.Empty
      If c.Parent IsNot Nothing Then
         parentorigin = c.Parent.PointToScreen(c.Location)
      End If
      Return New Point((clientorigin.X - parentorigin.X), (clientorigin.Y - parentorigin.Y))
   End Function 'ClientOriginRelativeToLocation

End Class ' TransparentPanel