title: Handle Mouse Hover on Titlebar of Form - Show Title of a Minimized MDI Child in ToolTip
body: <p>I'm looking for a message like <code>WM_NCMOUSEMOVE</code> that represents the mouse is hovering on title bar of a form.</p>
  
  <p>Currently I've put this code in child forms, but the problem is that they are many child forms and also it doesn't handle a mouse hover on title bar:</p>
  
  <pre class="lang-vb prettyprint-override"><code>Private Const WM_NCMOUSEMOVE = &amp;HA0
  Dim stado_min As Boolean
  
  Protected Overrides Sub DefWndProc(ByRef m As System.Windows.Forms.Message)
      If stado_min AndAlso CLng(m.Msg) = WM_NCMOUSEMOVE Then 
          form_principal.ToolTipTitulo.SetToolTip(Me, Label1.Text)
      End If
      MyBase.DefWndProc(m)
  End Sub
  
  Private Sub schanged() Handles MyBase.SizeChanged
      stado_min = (Me.WindowState = FormWindowState.Minimized)
  End Sub
  </code></pre>
  
  <p>In fact I'm looking for a solution to show title of an MDI child in tooltip when the mouse hovers over the minimized MDI child. How can I do that?</p>