使用API创建窗体（类似VC的创建过程）

are Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Public Declare Function MessageBox Lib "user32" Alias "MessageBoxA" (ByVal hwnd As Long, ByVal lpText As String, ByVal lpCaption As String, ByVal wType As Long) As Long
Public Declare Sub PostQuitMessage Lib "user32" (ByVal nExitCode As Long)


Public Type WNDCLASS
    style As Long
    lpfnwndproc As Long
    cbClsextra As Long
    cbWndExtra2 As Long
    hInstance As Long
    hIcon As Long
    hCursor As Long
    hbrBackground As Long
    lpszMenuName As String
    lpszClassName As String
End Type


Public Type POINTAPI
    x As Long
    y As Long
End Type


Public Type Msg
    hwnd As Long
    message As Long
    wParam As Long
    lParam As Long
    time As Long
    pt As POINTAPI
End Type

Public Const CS_VREDRAW = &H1
Public Const CS_HREDRAW = &H2

Public Const CW_USEDEFAULT = &H80000000

Public Const ES_MULTILINE = &H4&

Public Const WS_BORDER = &H800000
Public Const WS_CHILD = &H40000000
Public Const WS_OVERLAPPED = &H0&
Public Const WS_CAPTION = &HC00000 '' WS_BORDER Or WS_DLGFRAME
Public Const WS_SYSMENU = &H80000
Public Const WS_THICKFRAME = &H40000
Public Const WS_MINIMIZEBOX = &H20000
Public Const WS_MAXIMIZEBOX = &H10000
Public Const WS_OVERLAPPEDWINDOW = (WS_OVERLAPPED Or WS_CAPTION Or WS_SYSMENU Or WS_THICKFRAME Or WS_MINIMIZEBOX Or WS_MAXIMIZEBOX)

Public Const WS_EX_CLIENTEDGE = &H200&

Public Const COLOR_WINDOW = 5

Public Const WM_DESTROY = &H2
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_LBUTTONUP = &H202

Public Const IDC_ARROW = 32512&

Public Const IDI_APPLICATION = 32512&

Public Const GWL_WNDPROC = (-4)

Public Const SW_SHOWNORMAL = 1

Public Const MB_OK = &H0&
Public Const MB_ICONEXCLAMATION = &H30&


声明几个我们需要的变量、常量：

Public Const gClassName = "MyClassName"
Public Const gAppName = "My Window Caption"

Public gButOldProc As Long
Public gHwnd As Long, gButtonHwnd As Long, gEditHwnd As Long



入口函数：

Sub Main

代码如下：

Public Sub Main()

   Dim wMsg As Msg

   ''''Call procedure to register window classname. If false, then exit.
   If RegisterWindowClass = False Then Exit Sub
    
      ''''Create window
      If CreateWindows Then
     &nbs