windowDrawsSystemBarBackgrounds WTF

PhoneWindow.java

// Non-floating windows on high end devices must put up decor beneath the system bars and
// therefore must know about visibility changes of those.
if (!mIsFloating && ActivityManager.isHighEndGfx()) {
    if (!targetPreL && a.getBoolean(
	    R.styleable.Window_windowDrawsSystemBarBackgrounds,
	    false)) {
	setFlags(FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,
		FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS & ~getForcedWindowFlags());
    }
}