Window: Add window "token" type, unique for each window instance

Not recycled even for windows with same class/ID
Token may outlive window, unlike pointer

src/window.cpp

@@ -119,6 +119,7 @@ WindowDesc::WindowDesc(const char * const file, const int line, WindowPosition d
 	default_height_trad(def_height_trad)
 {
 	if (_window_descs == nullptr) _window_descs = new std::vector<WindowDesc*>();
+
 	_window_descs->push_back(this);
 }
 
@@ -1145,6 +1146,20 @@ Window *FindWindowByClass(WindowClass cls)
 	return nullptr;
 }
 
+/**
+ * Find any window by its token.
+ * @param token Window token
+ * @return Pointer to the found window, or \c nullptr if not available
+ */
+Window *FindWindowByToken(WindowToken token)
+{
+	for (Window *w : Window::IterateFromBack()) {
+		if (w->GetWindowToken() == token) return w;
+	}
+
+	return nullptr;
+}
+
 /**
  * Get the main window, i.e. FindWindowById(WC_MAIN_WINDOW, 0).
  * If the main window is not available, this function will trigger an assert.
@@ -1891,6 +1906,9 @@ void Window::InitNested(WindowNumber window_number)
  */
 Window::Window(WindowDesc *desc) : window_desc(desc), scale(_gui_scale), mouse_capture_widget(-1)
 {
+	static uint64_t last_window_token = 0;
+	last_window_token++;
+	this->window_token = WindowToken(last_window_token);
 }
 
 /**

src/window_func.h

@@ -18,6 +18,7 @@
 
 Window *FindWindowById(WindowClass cls, WindowNumber number);
 Window *FindWindowByClass(WindowClass cls);
+Window *FindWindowByToken(WindowToken token);
 Window *GetMainWindow();
 void ChangeWindowOwner(Owner old_owner, Owner new_owner);
 

src/window_gui.h

@@ -255,6 +255,8 @@ struct Window : ZeroedMemoryAllocator {
 	WindowClass window_class;        ///< Window class
 
 private:
+	WindowToken window_token;
+
 	/**
 	 * Helper allocation function to disallow something.
 	 * Don't allow arrays; arrays of Windows are pointless as you need
@@ -334,6 +336,8 @@ public:
 
 	void ChangeWindowClass(WindowClass cls);
 
+	WindowToken GetWindowToken() const { return this->window_token; }
+
 	/**
 	 * Set the timeout flag of the window and initiate the timer.
 	 */

src/window_type.h

@@ -10,6 +10,8 @@
 #ifndef WINDOW_TYPE_H
 #define WINDOW_TYPE_H
 
+#include "core/strong_typedef_type.hpp"
+
 /** %Window numbers. */
 enum WindowNumberEnum {
 	WN_GAME_OPTIONS_AI = 0,          ///< AI settings.
@@ -819,4 +821,6 @@ enum EventState {
 	ES_NOT_HANDLED, ///< The passed event is not handled.
 };
 
+using WindowToken = StrongType::Typedef<uint64_t, struct WindowTokenTag, StrongType::Compare>;
+
 #endif /* WINDOW_TYPE_H */