Jess Warden posted his opinion about the communication between designer to developer (thanks I learned from his blog a lot):”Designers have no idea the capability of the platform they are designing for“. Yes, especially for code-based Flash/Flex application, from Flash/Flex developer’s sight the design assets(bitmap, vector, shape) should be as light as possible, so we always use some tricks in Flash design to get best solution of it, while designers wouldn’t know it could be tiled with Graphics.beginBitmapFill(), using a very small bitmap comparing to draw a big bitmap which it couldn’t be used for Flash (or a big head for download time).