Windows D编程类封装初步学习并请教

首先把要请教的问题写在最顶部：
1。事件最好的包装方法是怎样的？怎样才能扩展它？可不可以给一个可运行的Minimal例程？
2。如何向WNDCLASS 的回调传递另一个类的成员方法，当然签名是相同的。直接传递是不行的，因delegate 和function不可隐式转换。

诚意请教，请赐教，谢谢！

dmd2031+windows xp sp3 +bud
compile:
bud -O -release -gui -cleanup winwrapapp.d

想着自己也能写一个GUI框架那多好啊，最起码也能学多一点东西，今天小试了一下用类封装Win32 编程，很明显事件部分是一大难点;另外D2的string 在与Win32 API 交互时的转换也很费事。做做笔记先。以下代码编译通过，可正常运行，但事件部分实在谈不上类封装。
注：1.为了支持中文，用了Win32 的Unicode API.
       2.Event类和Form类引用的Windows API 头文件来自D2 自带的std.c.windows.windows模块，如果改用win32包( http://www.dsource.org/projects/bindings/wiki/WindowsApi)的话则方便许多，因更全面，所以不用那么多的extern(Windows)...

主程序：

module winwrapApp;

import samsTools.form;

int main(string[] args)
{
	auto app=new Form("我的第一个WIN32 CLASS WRAPPER 窗口");
	return app.show;
}

Event类：

module samsTools.event;

//import win32.windows;
import std.c.windows.windows;

extern(Windows) int MessageBoxW(HWND,in wchar*,in wchar*,int);
class Event
{
	public:
	this()
	{
		//to-do 
	}
	
	//just a beginning test...
    //Oops!!!if wndProc is a non-static method,can not pass it to 
    //Form.WNDCLASS.lpfnWndProc directly!!!
	extern(Windows)
	static int wndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
	{
		switch(msg)
		{
			case WM_CREATE:
				//ti = new TrayIcon (hwnd,
              //TI_MYTRAYICON,LoadIconA(null, IDI_APPLICATION),"TrayIcon!");
	       //ti.show();
			break;
				case WM_LBUTTONDOWN:
				MessageBoxW(null,"左键被按下\nLeft button clicked!", "事件发生了",
					MB_ICONINFORMATION);
				break;
			/*
			case WM_RESIZE:
				showMessage("Windows 被更改了大小","事件通知");
				break;
			*/
			case WM_DESTROY:
				PostQuitMessage(0);
				break;
		
			default:
			break;
			
		}
		return DefWindowProcA(hwnd, msg, wparam, lparam);
	}
	private:
	enum EventType
	{
		Unknown=-1
		//to-do
	}
	

}

Form类：

module samsTools.form;

import samsTools.event;
//import win32.windows;

import std.c.windows.windows;

extern(Windows) HWND GetModuleHandleW(HWND);
extern(Windows) int MessageBoxW(HWND,in wchar*,in wchar*,int);
extern(Windows) HWND CreateWindowExW(
	int,const(wchar*),const (wchar*),int,int,int,int,int,HWND,HWND,HWND,void*);
extern(Windows) bool GetMessageW(LPMSG,HWND,int,int);
class Form
{
	public:
	this(const wstring title="Windows Template")
	{
		this._title=title;
		appInstance=GetModuleHandleW(null);
		//event=new Event;
		
		
	}
	int show()
	{
		if(! initApiClass)
			return 1;
		if(! initWidget)
			return 2;
		return loop;
	}

	HINSTANCE handle()
	{
		return appInstance;
	}
	
	const wstring title()
	{
		return _title;
	}
	
	private:
	HINSTANCE appInstance;
	HWND appWnd;
	WNDCLASS wc;
	MSG msg;
	const wstring _title;
	//Event event;

	

	bool initApiClass()
	{
		wc.lpszClassName = "winapi class";
		wc.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
		wc.lpfnWndProc = &Event.wndProc;
		wc.hInstance = appInstance;
		wc.hIcon = LoadIconA(null, IDI_APPLICATION);
		wc.hCursor = LoadCursorA(null, IDC_ARROW);
		wc.hbrBackground = cast(HBRUSH)(COLOR_BTNFACE + 1);
		wc.lpszMenuName = null;
		wc.cbClsExtra = wc.cbWndExtra = 0;
		if(!RegisterClassA(&wc))
		{
			MessageBoxW(null, "Window registration failure.", null, MB_ICONERROR);
			return false;
		}
		return true;
		
	}
	bool initWidget()
	{
		appWnd = CreateWindowExW(0, "winapi class",
		_title.ptr, WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		CW_USEDEFAULT, CW_USEDEFAULT, 300, 300, null, null, appInstance, null);
		if(appWnd is null)
		{
			MessageBoxW(null, "Window creation failure.", null, MB_ICONERROR);
			return false;
		}
		return true;
	}
	int loop()
	{
		while(GetMessageW(&msg, null, 0, 0) > 0)
		{
			TranslateMessage(&msg);
			DispatchMessageA(&msg);
		}
		return cast(int)msg.wParam;
	}
	
}