pub fn get_all_windows(&self) -> Result<Vec<xproto::Window>> {
        let mut all = Vec::new();
        for root in self.get_roots() {
            let some_windows = self.get_windows_for_root(root)?;
            for w in some_windows {
                all.push(w);
            }
        }
        Ok(all)
    }
Returns the child windows of all roots.
# Errors

Will error if root has no windows or there is an error
obtaining the root windows. See `get_windows_for_root`.
display-servers/x11rb-display-server/src/xwrap/getters.rs