Show and Hide a label in a panel in VB - vb.net

Question

I was surprised to find that in VB one can not easily set the font and backcolour of a tooltip item by it's default properties so I thought I would create my own.
Private aTimer As New System.Timers.Timer
Private Sub Panel1_MouseHover(sender As Object, e As EventArgs) Handles Panel1.MouseHover
Hover("How's about that")
End Sub
Private Sub Hover(ByRef Tip As String)
If Not lblToolTip.Visible Then
lblToolTip.Text = Tip
lblToolTip.Location = Me.PointToClient(MousePosition)
lblToolTip.Visible = True
lblToolTip.BringToFront()
StartTimer()
End If
End Sub
Private Sub StartTimer()
aTimer.Interval = 2000
AddHandler aTimer.Elapsed, New System.Timers.ElapsedEventHandler(AddressOf aTimer_Elapsed)
aTimer.Start()
End Sub
Sub aTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs)
aTimer.Stop()
lblToolTip.Visible = False
End Sub
Everything goes ok until I try to hide the label when I get the error -
'Cross - thread operation Not valid: Control 'lblToolTip' accessed from a thread other than the thread it was created on.'
I have researched the error for a couple of days but I am afraid it is a bit too deep a thread for an 80 old year after a stroke. I would appreciate any pointers to direct me to the solution.

Answer 1

You could have used a Forms Timer and not had this problem.
Since you didn't, replace your aTimer_Elapsed method with this.
Sub aTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs)
aTimer.Stop()
Me.BeginInvoke(Sub()
lblToolTip.Visible = False
End Sub)
End Sub

Answer 2

Try use Delegate
Private aTimer As New System.Timers.Timer
Private Delegate Sub SafeCallDelegate(ByVal label As Label, ByVal Visible As Boolean, ByVal Text As String)
Private Sub Panel1_MouseHover(sender As Object, e As EventArgs) Handles Panel1.MouseHover
Hover("How's about that")
End Sub
Private Sub StartTimer()
aTimer.Interval = 2000
AddHandler aTimer.Elapsed, New System.Timers.ElapsedEventHandler(AddressOf aTimer_Elapsed)
aTimer.Start()
End Sub
Sub aTimer_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs)
aTimer.Stop()
SetLabelProperty(lblToolTip, False)
End Sub
Private Sub SetLabelProperty(ByVal label As Label, ByVal Visible As Boolean, Optional ByVal Text As String = "")
If label.InvokeRequired Then
label.Invoke(New SafeCallDelegate(AddressOf SetLabelProperty), New Object() {label, Visible, Text})
Else
label.Visible = Visible
label.Location = Me.PointToClient(MousePosition)
label.Text = Text
lblToolTip.BringToFront()
End If
End Sub
Private Sub Hover(ByRef Tip As String)
If Not lblToolTip.Visible Then
SetLabelProperty(lblToolTip, True, Tip)
StartTimer()
End If
End Sub
Look this example:
Update Text Box Properly when Cross-threading in Visual Basic (VS 2012 V11)

Answer 3

This was the result
Public Sub ToolTip_Draw(sender As Object, e As DrawToolTipEventArgs)
e.DrawBackground()
e.DrawBorder()
e.Graphics.DrawString(e.ToolTipText, New Font("Arial", 10), System.Drawing.Brushes.Black, New PointF(2, 2))
End Sub
Public Sub ToolTip_Popup(sender As Object, e As PopupEventArgs)
Dim Sz As Size = TextRenderer.MeasureText(sender.GetToolTip(e.AssociatedControl), New Font("Arial", 10))
e.ToolTipSize = New Size(Sz.Width, Sz.Height + 4)
End Sub
The backcolour is set in the properties. The size is determined by the PipUp.