Niall,
When I preview a picture I can not edit from this page because the edit icon is not highlighted? I can only edit the picture in preview if I hold hold the ctrl key. Why is this? I used to work many moons ago and then I downloaded a update and stopped working.
Are you talking about the toolbar button that allows you to launch your photo into an external editor? How does holding down the Ctrl key help in this regard? (Generally holding down the Ctrl key and clicking causes the display of a contextual menu on Mac OS X.)
I just previewed an image in version 4.5.2 and the Edit button was enabled. Do you have a default external editor setup in your Photo Mechanic preferences? If you don't have an editor specified then the button will be disabled.
What version of Photo Mechanic had you last used before you upgraded?
-Kirk