Ctrl-C, Ctrl-X and Ctrl-V in textbox with Visual Basic.Net

Are you programming an MDI-application, and are you challenged by the fact that your MDI-childs won't process Ctrl-C, Ctrl-X and Ctrl-V in textboxes?

I did, and my first thought was, that Visual Basic.Net didn't support handling of Ctrl-C etc. in a textbox.

To test this, I made a small test-program (a simple SDI application with one form and one textbox). I discovered that Visual Basic.Net does handle these shortcuts properly in textboxes.

For me this was a kind of mystery for some time. However, after thinking about the result of my small test-program, I solved the problem.

MDI-parent and Ctrl-C

The reason for this phenomenon is that the MDI-parent receives these key events first. As there is no code to handle these events in the way you want, the application just ignores the whole event, leaving the user in dispair.

The solution is simple, in contrary to defining the reason for the problem, as usual. Place the following code in the top of the code-behind of the MDI-Parent:

'Use a Windows-api call to forward the triggered event
Private Declare Auto Function SendMessage Lib "user32" _

(ByVal hwnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr

'Override the Pressed Key Processing Routine of the MDI-Parent
Protected Overrides Function ProcessCmdKey _

(ByRef msg As System.Windows.Forms.Message, ByVal keyData As System.Windows.Forms.Keys) As Boolean

SendMessage(Me.ActiveMdiChild.Handle, msg.Msg, msg.WParam, msg.LParam)

End Function

After this, your MDI-Childs automatically handle the Ctrl-C, Ctrl-X and Ctrl-V etc. as you want.

So DON'T accept the solution to write event handlers for each textbox, with code like:

   If KeyCode = 67 And Shift = vbCtrlMask Then
       Clipboard.Clear
       Clipboard.SetText SomeTextbox.SelText
   End If