wake up windows main loop when updating fps, use PostMessage instead of the blocking SendMessage

src/main.cpp

@@ -23,6 +23,7 @@
 #include <sstream>
 
 #define WM_USER_CLOSE (WM_USER + 1)
+#define WM_USER_WAKEUP (WM_USER + 2)
 
 LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp);
 HINSTANCE hInst;
@@ -108,7 +109,7 @@ void destroy_window()
 {
     std::lock_guard<std::mutex> lock(main_task_mutex);
     main_tasklist.emplace_back([=] {
-        SendMessage(hWnd, WM_USER_CLOSE, 0, 0);
+        PostMessage(hWnd, WM_USER_CLOSE, 0, 0);
     });
 }
 
@@ -196,10 +197,13 @@ void win32_update_fps(int frames)
     else
         swprintf_s(title_fps, L"%s - %d fps", window_title, frames);
 
-    std::lock_guard<std::mutex> lock(main_task_mutex);
-    main_tasklist.emplace_back([] {
-        SetWindowText(hWnd, title_fps);
-    });
+    {
+        std::lock_guard<std::mutex> lock(main_task_mutex);
+        main_tasklist.emplace_back([] {
+            SetWindowText(hWnd, title_fps);
+        });
+    }
+    PostMessage(hWnd, WM_USER_WAKEUP, 0, 0);
 }
 
 void win32_show_cursor(bool visible)