my latest version of my aero glass skin now has an crude option to import a custom image (you have to crop it to 666x786 and import it with reshacker), and if your start menu is to far from the dimensions of mine, the image might be to stretched..
but all the settings can be edited ofcourse, and all the variables you would need to change are under 1 option [CustomImage] , or if your more familiar with photo manipulation you can always stretch the side thats to small for your base image, so when it stretches its normal
im thinking of splitting it off as a new custom skin (as some of my options arnt compatable, and it would probably warrant several options of its own), depending on if IVO has anything to say about this idea (which would be better, as it would allow an overlay defined by the skin, and a background image defined by the user, giving best of both worlds
