Thanks for your answer. I changed vector of object pointers to vector of objects (changed RenderTexture to RenderTexture* to make copy assignment possible) and now main() looks like this:
int main()
{
std::vector<Menu> Menus;
Menus.push_back(Menu());
Menus.back().DrawMenu();
return 0;
}
This time, I get read access violation "
this was 0x30" on the line with drawing to the window.
EDIT: I simplified code so much (to show a minimal example) that I deleted part with creating window, thats why I got read access violation. Problem is solved now. Cheers!