The horizontal screen coordinate of the top of the stimulus.
<button> <clock> <picture> <shape> <text> <video>
This property returns the top of the stimulus in screen pixels.
The following displays the value of top in a text stimulus:
<text sometext>
/ items= ("top = <% text.foo.top %>")
</text>
The following displays the value of top in an instruction page:
<page somepage>
top = <% defaults.top %>
</page>