Xaml :
<Grid>
<Canvas Background="Transparent" Name="canvas" Height="260" Width="280" MouseMove="canvas_MouseMove" >
<Button Width="31" Height="30" Name="move" ></Button>
</Canvas>
</Grid>
c# :
private void canvas_MouseMove(object sender, MouseEventArgs e)
{
Point p = e.GetPosition(canvas);
move.Margin = new Thickness(p.X, p.Y, 0, 0);
}