implement shared cancellable reference

src/app/browser/window/tab/item/page/client.rs

@@ -1,11 +1,18 @@
-/// Single client instance holder for `Page` object.
+use gtk::gio::Cancellable;
+use std::cell::RefCell;
+
+/// Multi-client holder for single `Page` object
 ///
-/// unlike new client instance init on every page open,
-/// this solution provide additional client-side features
-/// e.g. session cache management on certificate change in runtime
+/// Unlike init new client instance on every page load,
+/// this struct creates single holder for different protocol drivers;
+/// it also provides additional client-side features
+/// e.g. session resumption or multi-thread connection management (depending of client type selected)
 pub struct Client {
+    // Shared reference to cancel async operations
+    pub cancellable: RefCell<Cancellable>,
+    // Clients
     pub gemini: gemini::Client,
-    // other supported clients here..
+    // other clients..
 }
 
 impl Client {
@@ -14,6 +21,7 @@ impl Client {
     /// Create new `Self`
     pub fn new() -> Self {
         Self {
+            cancellable: RefCell::new(Cancellable::new()),
             gemini: gemini::Client::new(),
         }
     }