[texworks] Minor bug in Preview

[Bruno Voisin]

Imagine you've got this (on the Mac, TeXworks r333):

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 1.png
Type: image/png
Size: 188892 bytes
Desc: not available
URL: <http://tug.org/pipermail/texworks/attachments/20090722/a876e189/attachment-0002.png>
-------------- next part --------------



And you press the green Magnify button near the top left corner of the  
window. You'll get something like that:

-------------- next part --------------
A non-text attachment was scrubbed...
Name: Image 2.png
Type: image/png
Size: 203115 bytes
Desc: not available
URL: <http://tug.org/pipermail/texworks/attachments/20090722/a876e189/attachment-0003.png>
-------------- next part --------------



Namely a white unrendered area starting at the previously hidden part  
of the previewed document.

Bruno Voisin