question: toggle the visibility of the system ui . concode_field_sep OnVisibilityChangeListener mOnVisibilityChangeListener concode_elem_sep int FLAG_LAYOUT_IN_SCREEN_OLDER_DEVICES concode_elem_sep View mAnchorView concode_elem_sep Activity mActivity concode_elem_sep int FLAG_FULLSCREEN concode_elem_sep int mFlags concode_elem_sep OnVisibilityChangeListener sDummyListener concode_elem_sep int FLAG_HIDE_NAVIGATION concode_field_sep void hide concode_elem_sep void show concode_elem_sep void setOnVisibilityChangeListener concode_elem_sep void setup concode_elem_sep SystemUiHider getInstance concode_elem_sep boolean isVisible concode_elem_sep void onVisibilityChange concode_elem_sep void onVisibilityChange
target: void function ( ) { if ( isVisible ( ) ) { hide ( ) ; } else { show ( ) ; } }