embeded qt configure option, some I don't know what's meanning

[binbin]

http://doc.qt.nokia.com/qtextended4.4/buildsystem/over-configure-options-qt-embedded-1.html

I don't know what the decoration'meanning is, and the style point what? please tell me detail.
sorry,my english is poor, thanks verry much.

-qt-decoration-<style>