Fix to sending key signals when window focus lost (#845)

When window focus has just been lost, key pressed events aren't ignored

src/window/window_wrapper/keyboard_manager.rs

@@ -32,12 +32,12 @@ impl KeyboardManager {
     pub fn handle_event(&mut self, event: &Event<()>) {
         match event {
             Event::WindowEvent {
-                event: WindowEvent::Focused(focused),
+                event: WindowEvent::Focused(_focused),
                 ..
             } => {
-                // The window was just focused, so ignore keyboard events that were submitted this
+                // When window is just focused or lost it's focus, ignore keyboard events 
-                // frame.
+                // that were submitted this frame
-                self.ignore_input_this_frame = *focused;
+                self.ignore_input_this_frame = true;
             }
             Event::WindowEvent {
                 event: