I've noticed that controls do not raise a Validating event if they are 
contained in a ToolStripDropDown via a ToolStripControlHost item.  Please run 
the following sample and follow the instructions on the form to reproduce 
this issue:

------------------------------------

Public Class Form1
  Inherits Windows.Forms.Form

  Public ToolStripPanel As Windows.Forms.ToolStripPanel
  Public ToolStrip As Windows.Forms.ToolStrip
  Public Item1 As Windows.Forms.ToolStripMenuItem
  Public ControlHost1 As Windows.Forms.ToolStripControlHost

  Public InstructionsLabel As Windows.Forms.Label

  Public DataInput1 As DataInput
  Public DataInput2 As DataInput

  Public Sub New()
    MyBase.New()

    Me.Size = New Drawing.Size(400, 300)

    Me.DataInput1 = New DataInput
    Me.DataInput1.Name = "DataInput1"
    Me.DataInput1.Dock = DockStyle.Fill
    Me.DataInput1.Button.Text = "Button1"

    Me.DataInput2 = New DataInput
    Me.DataInput2.Name = "DataInput2"
    Me.DataInput2.Dock = DockStyle.Fill
    Me.DataInput2.Button.Text = "Button2"

    Me.ControlHost1 = New Windows.Forms.ToolStripControlHost(Me.DataInput2)

    Me.Item1 = New Windows.Forms.ToolStripMenuItem("Item")
    Me.Item1.DropDownItems.Add(Me.ControlHost1)

    Me.ToolStrip = New Windows.Forms.ToolStrip
    Me.ToolStrip.Items.Add(Me.Item1)

    Me.ToolStripPanel = New Windows.Forms.ToolStripPanel
    Me.ToolStripPanel.Dock = DockStyle.Top
    Me.ToolStripPanel.Controls.Add(Me.ToolStrip)

    Me.InstructionsLabel = New Windows.Forms.Label
    Me.InstructionsLabel.Text = "Click inside of the TextBox on this form, 
then click Button1.  Notice that the Validating event is raised.  Now, click 
the ToolStrip item to show its DropDown.  Next, click inside of the 
DropDown's TextBox and then click Button2.  Notice that the Validating event 
for the DropDown's TextBox is not raised."
    Me.InstructionsLabel.Height = 128
    Me.InstructionsLabel.Dock = DockStyle.Bottom

    Me.Controls.Add(Me.DataInput1)
    Me.Controls.Add(Me.InstructionsLabel)
    Me.Controls.Add(Me.ToolStripPanel)
  End Sub

End Class

Public Class DataInput
  Inherits Windows.Forms.Panel

  Public TextBox As Windows.Forms.TextBox
  Public Button As Windows.Forms.Button

  Public Overrides Function GetPreferredSize(ByVal proposedSize As 
System.Drawing.Size) As System.Drawing.Size
    Dim width As Integer = Me.TextBox.Width
    Dim height As Integer = (Me.TextBox.Height + Me.Button.Height)
    Return New Drawing.Size(width, height)
  End Function

  Public Sub New()
    MyBase.New()

    Me.TextBox = New Windows.Forms.TextBox
    
    Me.Button = New Windows.Forms.Button
    Me.Button.Width = Me.TextBox.Width
    Me.Button.Top = Me.TextBox.Bottom

    Me.Controls.Add(Me.TextBox)
    Me.Controls.Add(Me.Button)

    AddHandler Me.TextBox.Validating, AddressOf Me.TextBox_Validating
    AddHandler Me.TextBox.Validated, AddressOf Me.TextBox_Validated

    Me.Size = Me.GetPreferredSize(Drawing.Size.Empty)
  End Sub

  Private Sub TextBox_Validating(ByVal sender As Object, ByVal e As 
System.ComponentModel.CancelEventArgs)
    MessageBox.Show(System.String.Format("Validating {0}", Me.Name))
  End Sub

  Private Sub TextBox_Validated(ByVal sender As Object, ByVal e As 
System.EventArgs)
    MessageBox.Show(System.String.Format("Validated {0}", Me.Name))
  End Sub

End Class

------------------------------------

Is this a known issue and, more importantly, are there any workarounds?

Thanks for any help!
Lance

Hi Lance,

Yes, I can reproduce your problem with the code snippet you provided. 

Actually, this is has been reported before due to the behavior of 
ToolStrip. Internally, the Validating event is fired during the focus 
change between controls. The design rational for ToolStrip is that it will 
not grab focus from the controls on the form. If we click textbox or button 
in ToolStrip, it will not steal focus from the original control, so no 
validating is triggered. For details, please refer to the original reported 
issue in the link below:
"Control validation events not fired when toolstrip button is clicked"
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?Feedba
ckID=117084

However, your scenairo is more complex than the customer in above link, 
since you wanted to perform validating over the TextBox in the ToolStrip. 
Since the TextBox in the ToolStrip never got focus, calling Form.Validate() 
method as suggested in the above link will not work correctly. 

I have tried to set the focus programatically to the TextBox in the 
ToolStrip, however, it does not work either. Without setting the focus onto 
the TextBox, there is no single place(LostFocus) to perform validating, so 
I do not think there is any perfect workaround for your scenario. The only 
workaround I can think of is calling the TextBox_Validating and 
TextBox_Validated methods in all the places you may go away after finished 
editing in ToolStrip TextBox. For example, you have to call these 2 methods 
in Button2.Click event handler like below:

AddHandler Me.DataInput2.Button.Click, AddressOf Button2_Click
Private Sub Button2_Click(ByVal sender As Object, ByVal e As 
System.EventArgs)
    Me.DataInput2.TextBox_Validating(Me.DataInput2, New 
System.ComponentModel.CancelEventArgs())
    Me.DataInput2.TextBox_Validated(Me.DataInput2, New EventArgs())
End Sub

Public Sub TextBox_Validating(ByVal sender As Object, ByVal e As 
System.ComponentModel.CancelEventArgs)
    MessageBox.Show(System.String.Format("Validating {0}", Me.Name))
End Sub

Public Sub TextBox_Validated(ByVal sender As Object, ByVal e As 
System.EventArgs)
    MessageBox.Show(System.String.Format("Validated {0}", Me.Name))
End Sub

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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