void CBtnEnableDlg::OnButton1() 

{

  SetTimer(1,100,NULL);

}

void CBtnEnableDlg::OnTimer(UINT nIDEvent) 

{

 HWND hWnd,hWndChild;

  POINT point;

    hWnd=::GetForegroundWindow();

    GetCursorPos(&point);

    ::ScreenToClient(hWnd,&point);

    hWndChild=::ChildWindowFromPoint(hWnd,point);

    if(::IsWindowEnabled(hWndChild)==0)

    {            

    ::EnableWindow(hWndChild,1);

  }             

    CDialog::OnTimer(nIDEvent);

}

Imports System.Runtime.InteropServices

Public Class Form1

    <DllImport("user32.dll")> _

Private Shared Function ChildWindowFromPoint(ByVal hWndParent As IntPtr, ByVal Point As Point) As IntPtr

    End Function

    <DllImport("user32.dll", SetLastError:=True)> _

Private Shared Function GetForegroundWindow() As IntPtr

    End Function

    <DllImport("user32.dll")> _

Private Shared Function IsWindowEnabled(ByVal hWnd As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean

    End Function

    Declare Function EnableWindow Lib "user32" (ByVal hwnd As IntPtr, ByVal fEnable As Integer) As Integer

    <DllImport("user32.dll", SetLastError:=True)> _

Private Shared Function ScreenToClient(ByVal hWnd As IntPtr, ByRef lpPoint As Point) As Boolean

    End Function

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

        Dim p As Point = MousePosition

        Dim hWnd, hWndChild As IntPtr

        hWnd = GetForegroundWindow()

        ScreenToClient(hWnd, p)

        hWndChild = ChildWindowFromPoint(hWnd, p)

        If Not IsWindowEnabled(hWndChild) Then

            EnableWindow(hWndChild, 1)

        End If  '更多.net源码和教程，来自[乐博网 www.lob.cn]

    End Sub

    Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged

        Timer1.Enabled = CheckBox1.Checked

    End Sub

End Class