Ok, first thing's first.
Pixel PerfectPixel Perfect means that the coordinate system used by localtransforms corrosponds with the pixels on the physical screen. That means that if you're on an iPhone 4 in portrait mode, the screen is 640x960. On an iPad, however, the screen size is 768x1024. Both the sizes and the aspect changes. If your UIRoot is set to pixel perfect, then if your assets fit perfectly on the iPhone, they will be too small to fill corner to corner on the ipad, just because the size is just bigger there.
Fixed sizeFixed size is a way for you to set the height of the screen manually. Let that part sink in.
The aspect of the screen will be calculated from the physical resolution, but it will calculate the width based on the manualHeight that is input in UIRoot.
Examples:
iPhone 4 is 640x960 pixels in portrait. I set my manualHeight to 960. Now the coordinate system under UIRoot will fit so that I can assume that the width is 640 and the height is 960.
What happens on on Ipad!?
Well, if my manualHeight is still set to 960, but the physical height is actually 1024. Then you have to calculate how wide the internal coordinate system (Virtual Pixels) actually is now:
PhysicalWidth / PhysicalHeight * manualHeight = calculatedWidth
768 / 1024 * 960 = 720. If you assume a manual height of 960, then the width of the screen is 720 on the iPad.
Does that make sense?
Solutions for your specific problems become more readily available once you understand this. Either, scale the manual height up so it fits better; have more stuff on the sides that's outside the screen on smaller device; or something entirely different on screen in different sizes. There are many possible solutions.
