message: Convert cout debug messages to exceptions in WindowStack
diff: #include <algorithm>
  #include <iostream>
  -
  +#include <stdexcept>
  /**
  @@ -17,8 +17,7 @@ void WindowStack::addWindow(Window* window)
  {
  if (find(mWindowList.begin(), mWindowList.end(), window) != mWindowList.end())
  {
  - std::cout << "WindowStack::addWindow(): Attempting to add a Window that's already in this stack." << std::endl;
  - return;
  + throw std::runtime_error("WindowStack::addWindow(): Attempting to add a Window that's already in this stack.");
  }
  mWindowList.push_back(window);
  @@ -73,8 +72,7 @@ void WindowStack::bringToFront(Window* window)
  const auto windowPosition = find(mWindowList.begin(), mWindowList.end(), window);
  if (windowPosition == mWindowList.end())
  {
  - std::cout << "WindowStack::bringToFront(): Window is not managed by this stack." << std::endl;
  - return;
  + throw std::runtime_error("WindowStack::bringToFront(): Window is not managed by this stack.");
  }
  if (windowPosition == mWindowList.begin())
  {
  