add: Allow to sync UI interactions on any callable

src/app/rmrf.cpp

+#include <iostream>
+
 #include "ui/View.h"
 
 int main() {
-    auto ui_handle = std::make_shared<rmrf::ui::display>();
+    using rmrf::ui::display;
+
+    auto h_nc = std::make_shared<display>();
+
+    h_nc->sync([](const display::ptr_type &) {
+        std::cout << "Hello World!\n" << std::flush;
+    });
 
     return 0;
 }

src/app/rmrf.ldflags

--lncursesw
+-lncursesw -pthread

src/ui/View.cpp

@@ -8,7 +8,7 @@
 
 namespace rmrf::ui {
 
-display::display() {
+display::display() : m{} {
     initscr();
 }
 

src/ui/View.h

 #pragma once
 
+#include <functional>
 #include <memory>
+#include <shared_mutex>
 
 namespace rmrf::ui {
 
-struct display : std::enable_shared_from_this<display> {
+class display : public std::enable_shared_from_this<display> {
+public:
+    typedef display self_type;
+    typedef std::shared_ptr<self_type> ptr_type;
+
+private:
+    typedef std::shared_mutex mutex_type;
+    typedef std::lock_guard<mutex_type> lock_type;
+    mutable mutex_type m;
+
+public:
     display();
     ~display();
+
+public:
+    template<typename F, typename ...Args>
+    decltype(auto) sync(F &&f, Args &&... args) {
+        lock_type lock(m);
+
+        return std::forward<F>(f)(shared_from_this(), std::forward<Args>(args)...);
+    }
+
 };
 
 }