/vendor/mediatek/proprietary/packages/apps/MtkSettings/res/xml/system_dashboard_fragment.xml
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:settings="http://schemas.android.com/apk/res-auto"
android:key="system_dashboard_screen"
android:title="@string/header_category_system"
settings:initialExpandedChildrenCount="4">
意思是，超过4个菜单则折叠隐藏起来，否则没超过直接平铺展开显示！
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
final PreferenceScreen screen = getPreferenceScreen();
// We do not want to display an advanced button if only one setting is hidden
if (getVisiblePreferenceCount(screen) == screen.getInitialExpandedChildrenCount() + 1) {
screen.setInitialExpandedChildrenCount(Integer.MAX_VALUE);
}
}