Can the image representing the rendering in Page Editor be customized? I have been able to update the text below the image by changing the Display Name to "Call To Action"... was just wondering if I could update the image above the text with a snip from the comp instead of the little blue outlined box.
Sitecore 7 Update-1
You can change the image by editing the "Thumbnail" field on the Sublayout/Rendering. The field is hidden by default though, so you will need to check the "Standard Fields" checkbox on the "View" ribbon.