register mux as a gui thread local variable

src/main.rs

@@ -125,6 +125,7 @@ fn main() -> Result<(), Error> {
     };
 
     let mux = Rc::new(mux::Mux::default());
+    Mux::set_mux(&mux);
 
     let gui_system = opts.gui_system.unwrap_or(config.gui_system);
     let gui = gui_system.try_new(&mux)?;

src/mux/mod.rs

@@ -101,11 +101,31 @@ impl<'a> TerminalHost for Host<'a> {
     fn set_title(&mut self, _title: &str) {}
 }
 
+thread_local! {
+    static MUX: RefCell<Option<Rc<Mux>>> = RefCell::new(None);
+}
+
 impl Mux {
     pub fn set_spawner(&self, spawner: Spawner) {
         *self.spawner.borrow_mut() = Some(spawner);
     }
 
+    pub fn set_mux(mux: &Rc<Mux>) {
+        MUX.with(|m| {
+            *m.borrow_mut() = Some(Rc::clone(mux));
+        });
+    }
+
+    pub fn get() -> Option<Rc<Mux>> {
+        let mut res = None;
+        MUX.with(|m| {
+            if let Some(mux) = &*m.borrow() {
+                res = Some(Rc::clone(mux));
+            }
+        });
+        res
+    }
+
     pub fn get_tab(&self, tab_id: TabId) -> Option<Rc<Tab>> {
         self.tabs.borrow().get(&tab_id).map(Rc::clone)
     }