title: Ribbon Invalidate does not work
body: <p>I have a simple outlook ribbon with an editBox. Once the user clicks the send button, I capture the string in the editBox and use it in the Application_ItemSend..</p>
  
  <p>My problem is, after the function is done, I want to RESET the UI of the ribbon (just the editBox) so that the user won't have the previously typed string in the same box when opening up a new message screen. I tried the Ribbon.Invalidate but I can't seem to get rid of that string value. When I re-open the "New Email" screen, the old value is still there.</p>
  
  <p>Here is the code:</p>
  
  <pre><code>&lt;customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui" onLoad="Ribbon_Load_2010"&gt;
  &lt;ribbon&gt;
  &lt;tabs&gt;
    &lt;tab idMso="TabNewMailMessage"&gt;
      &lt;group id="TaskManager" insertBeforeMso="GroupSend" label="Task Manager"&gt;
        &lt;editBox id="editboxTaskID" label="Task ID #: " onChange="editboxTaskID_OnChange" 
  imageMso="RecordsAddFromOutlook" sizeString="wwwwww"/&gt;
      &lt;/group&gt;
    &lt;/tab&gt;
  &lt;/tabs&gt;
  &lt;/ribbon&gt;
  &lt;/customUI&gt;
  </code></pre>
  
  <p>And the VB Code:</p>
  
  <pre><code>&lt;Runtime.InteropServices.ComVisible(True)&gt; _
  Public Class CustomRibbon
  Implements Office.IRibbonExtensibility
  
  Private ribbon As Office.IRibbonUI
  Public strTask_ID As String = ""
  
  Public Sub New()
  
  End Sub
  
  Public Function GetCustomUI(ByVal ribbonID As String) As String Implements Office.IRibbonExtensibility.GetCustomUI
      Return GetResourceText("Addin.Ribbon.xml")
  End Function
  
  Private Sub Application_ItemSend(ByVal Item As Object, ByRef Cancel As Boolean)
      Me.ribbon.Invalidate()
      Try
  
   'SOME CODE HERE WHICH WORKS FINE!
  
      Catch ex As Exception
      End Try
  
  End Sub
  
  
  'Create callback methods here. For more information about adding callback methods, select the Ribbon XML item in Solution Explorer and then press F1.
  Public Sub Ribbon_Load_2010(ByVal ribbonUI As Office.IRibbonUI)
      Me.ribbon = ribbonUI
      AddHandler Globals.ThisAddIn.Application.ItemSend, AddressOf Application_ItemSend
  End Sub
  
  Public Sub editboxTaskID_OnChange(ByVal control As Office.IRibbonControl, ByVal Text As String)
      strTask_ID = Text
  End Sub
  
  Public Sub AttachmentRibonClick(ByVal control As Microsoft.Office.Core.IRibbonControl)
      Globals.ThisAddIn.TriggerTaskWindow("Attachment")
  End Sub
  
  Private Shared Function GetResourceText(ByVal resourceName As String) As String
      Dim asm As Reflection.Assembly = Reflection.Assembly.GetExecutingAssembly()
      Dim resourceNames() As String = asm.GetManifestResourceNames()
      For i As Integer = 0 To resourceNames.Length - 1
          If String.Compare(resourceName, resourceNames(i), StringComparison.OrdinalIgnoreCase) = 0 Then
              Using resourceReader As IO.StreamReader = New IO.StreamReader(asm.GetManifestResourceStream(resourceNames(i)))
                  If resourceReader IsNot Nothing Then
                      Return resourceReader.ReadToEnd()
                  End If
              End Using
          End If
      Next
      Return Nothing
  End Function
  End Class
  </code></pre>