message: remove undefined function
diff: @@ -24,5 +24,4 @@ bool ImGui_ImplGlfwGL3_CreateDeviceObjects();
  void ImGui_ImplGlfwGL3_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods);
  void ImGui_ImplGlfwGL3_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset);
  void ImGui_ImplGlfwGL3_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods);
  -void ImGui_ImplGlfwGL3_CharCallback(GLFWwindow* window, unsigned int c);
  