Core tool for placing UI elements on screen is EZAlignment (available from Main Menu -> Components -> EZ GUI -> EZLayout -> Alignment). UI root contains EZAlignment control that detects viewport size and sets it extents to appropriate values. Root aligner works automatically and ignores user defined size and margins.
Child UI elements can align themselves relative to parent elements also by using Alignement, but with custom margins, size and alignment mode. Sizes in UI are defined in pixels, most of the time one pixel is mapped to one world unit. Margins and sizes can be also defined in percentage from parent size, instead of pixels. That is achieved by setting appropriate value type from PIXELS to PARENT_SIZE_PERCENTS.
Following horizontal alignment modes are available in aligner:
LEFT – child aligns its left edge to the parents’ left edge, left margin is taken into account.
RIGHT – child aligns its right edge to the parents’ right edge, right margin is taken into account.
CENTER – child aligns its center to the parents’ center, both left and right margins are taken into account.
STRETCH – child takes all parents’ width, both left and right margins are taken into account.
http://tools.artofbytes.com/ezdata/documentation
