Function parse_net_wm_state_fullscreen 

pub(crate) fn parse_net_wm_state_fullscreen(text: &str) -> bool

Linux xprop -id <id> _NET_WM_STATE: true iff _NET_WM_STATE_FULLSCREEN is present. Crucially _NET_WM_STATE_MAXIMIZED_* must NOT match — a maximised window with the taskbar visible is the case we exclude.