Major BugFix: avoid default gst g_main_context

Do NOT update g_main_context at RenderingManager update. Do not use g_main_context for Dialogs. Do not rely on default g_main_context for Device discoverer (implemented a thread save g_main_loop dedicated).

RenderingManager.cpp

@@ -368,9 +368,6 @@ void Rendering::draw()
     // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
     glfwPollEvents();
 
-    // no g_main_loop_run(loop) : update global GMainContext
-    g_main_context_iteration(NULL, FALSE);
-
 }
 
 void Rendering::terminate()