Touch event in wpf interfering with other events - wpf

Question

Help!
Been wrestling with a problem using Touch events in a wpf application I am developing.
Let me set the scene...
I have a main window (fmMainWindow) that has a Textbox on it. The window is coded to be centred to the screen when open. On the TouchUp event of the Textbox, I have code that opens up another window (fmKeypad_Numeric) using the syntax ShowDialog. This window is also centred. It is a numeric keypad with numbered buttons on it.
My problem is that the Touch Event used on the main window is having an affect on the Click events of the buttons on the window it opens.
It looks like wherever on the screen the Touch Event occurred, that the button on the next window opened at the same position seems to initially have some sort of 'focus' (it appears as if the mouse is hovered over it).
If you click the button that initially has the 'focus', the click event fires as expected.
If however you first click one of the other buttons that doesn't have the 'focus' its click event does not fire. It takes a second click for it to fire??
I have used Snoop to see how the events fire and when you click one of the other buttons that doesn't initially have the 'focus', Events related to the button that has the 'focus' fire??
Anyone got any ideas? I've spent days on this one.
Code for the two windows is below
Many thanks in advance,
Rhyd.
fmMainWindow
<Window x:Class="fmMainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Main Window" SizeToContent="WidthAndHeight" ResizeMode="NoResize" FontFamily="Century Gothic">
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="0">
<TextBox Name="tbTest" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="180,10,10,0" Width="150" Height="50" BorderBrush="#FF1B378B" Background="#FFEC1212"/>
</Grid>
Public Class fmMainWindow
Public Sub New()
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
Me.WindowStartupLocation = Windows.WindowStartupLocation.CenterScreen
End Sub
Private Sub tbTest_TouchUp(sender As Object, e As TouchEventArgs) Handles tbTest.TouchUp
e.Handled = True
Dim myKeypad As New fmKeypad_Numeric()
myKeypad.ShowDialog()
myKeypad.Close()
End Sub
End Class
fmKeypad_Numeric
<Window x:Class="fmKeypad_Numeric"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Keypad_Numeric" SizeToContent="WidthAndHeight" ResizeMode="NoResize" FontFamily="Century Gothic" FontSize="30" Left="10">
<Window.Resources>
<Style TargetType="{x:Type Button}" BasedOn="{StaticResource {x:Type Button}}">
<Setter Property="Height" Value="70" />
</Style>
</Window.Resources>
<Grid Name ="grKeypad" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<TextBox Name="tbNumber" HorizontalAlignment="Left" VerticalAlignment="Top" HorizontalContentAlignment="Right" Text="" Width="230" IsReadOnly="True" Margin="10,10,0,0"/>
<Button Name="bu7" Content="7" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10,70,0,0" Width="70" />
<Button Name="bu8" Content="8" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="90,70,0,0" Width="70" />
<Button Name="bu9" Content="9" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="170,70,10,0" Width="70" />
<Button Name="bu4" Content="4" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10,150,0,0" Width="70" />
<Button Name="bu5" Content="5" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="90,150,0,0" Width="70" />
<Button Name="bu6" Content="6" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="170,150,10,0" Width="70" />
<Button Name="bu1" Content="1" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10,230,0,0" Width="70" />
<Button Name="bu2" Content="2" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="90,230,0,0" Width="70" />
<Button Name="bu3" Content="3" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="170,230,10,0" Width="70" />
<Button Name="bu0" Content="0" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="10,310,0,0" Width="70" />
</Grid>
Public Class fmKeypad_Numeric
Public Sub New()
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
Me.WindowStartupLocation = Windows.WindowStartupLocation.CenterScreen
End Sub
Private Sub Button_Click(sender As Object, e As RoutedEventArgs) Handles bu0.Click, bu1.Click, bu2.Click, bu3.Click, bu4.Click, bu5.Click, bu6.Click, bu7.Click, bu8.Click, bu9.Click
Dim myButtonName As String
Dim myTextToAdd As String = ""
myButtonName = CType(sender, Button).Name
myTextToAdd = Replace(myButtonName, "bu", "")
Me.tbNumber.Text = Me.tbNumber.Text & myTextToAdd
End Sub
End Class