Find location of part of an image on screen?
<p>I have an image, 480px wide. It is mostly transparent but has a tab protruding from it. Is there a way to get the x-coordinates of the left and right edge of the protrusion? It will stretch depending on screen size, so I don't think I can hard code it.</p>

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  <p><em><strong></em>__<em>_</em>__<em>_</em>__</strong>[====]<strong><em>_</em>__</strong></p>
</blockquote>
