Put this in your form:

Code:
Private Delegate Sub SetPTabColor_Delegate(ByVal tc As DevComponents.DotNetBar.eTabItemColor)
Private Sub SetPTabColor(ByVal tc As DevComponents.DotNetBar.eTabItemColor)
     Me.dockMessages.PredefinedTabColor = tc
End Sub
Private Sub MySub()
        Dim deleg As New SetPTabColor_Delegate(AddressOf SetPTabColor)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Red)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Green)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Red)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Green)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg, DevComponents.DotNetBar.eTabItemColor.Red)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Green)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Red)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Green)
        System.Threading.Thread.Sleep(500)
        Me.Invoke(deleg,DevComponents.DotNetBar.eTabItemColor.Red)
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
     Call (New Threading.Thread(AddressOf MySub) With {.IsBackground = True}).Start()
End Sub