IsMouseOver property is not updated more than once for a Thumb

I have fol开发者_如何学运维lowing grid which is resizable through Thumb:

<Grid x:Name="ROIGridFor10X" 
      Width="1360" 
      Height="1023" 
      Visibility="Hidden" 
      Cursor="Arrow" 
      Canvas.Left="0" 
      Canvas.Top="0">

    <Thumb x:Name="thumb" 
           Cursor="SizeWE" 
           Width="{Binding Path=Width, ElementName=ROIGridFor10X}" 
           Height="{Binding Path=Height, ElementName=ROIGridFor10X}" 
           DragStarted="OnDragStarted" 
           DragDelta="Resize" />            

</Grid>

Other thumbs are omitted for the sake of brevity. The drag through the thumb is only possible for the for the first time only. After that the thumb is not being shown at all. Upon Snooping i found that thumb's sMouseOver property is not being updated after the first time. Can anyone suggest what may be the possible problem?

probably means something is causing your thumb to stop being found in a hit test... possible reasons for that are:

1) the mouse is hit testing to something else on top of the thumb
2) the mouse is captured to something else
3) the thumb has been given a null background and no content
4) the thumb has IsHitTestVisible set to false

snoop can help you check which if any of these are the case