Question

Below is a very crude start to a thumb template that eventually might look like a respectable popup window. Obviously the user can drag it around from any location therein. Is there any way to make it so it can only be dragged from the top AliceBlue border? Put another way, it is possible to disable dragging from the second border?

    <Popup x:Name="MyPopup">
        <Popup.Child>
            <Thumb DragDelta="Thumb_DragDelta">
                <Thumb.Template>
                    <ControlTemplate>
                        <StackPanel Margin="20">
                            <Border Height="20" Width="200" BorderBrush="Black" BorderThickness="2,2,2,0" CornerRadius="3,3,0,0" Background="AliceBlue"></Border>
                            <Border Height="200" Width="200" BorderBrush="Black" BorderThickness="2,0,2,2" Background="Bisque"></Border>
                        </StackPanel>
                    </ControlTemplate>
                </Thumb.Template>
            </Thumb>
        </Popup.Child>
    </Popup>

Answer 1

I haven’t tested this so it’s a bit of a guess. Add an event handler to the MouseLeftButtonDown event on AliceBlue Border. In the event handler:-

e.Handled = true;