Programming User Interface in InstallScript

// subclass.cpp : Defines the exported functions for the DLL application.
//
#include "stdafx.h"
static WNDPROC oldstaticproc;
static int nCtrlID;

long __stdcall StaticProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{	
	switch(msg)
	{
		case WM_CTLCOLORSTATIC: //WM_CTLCOLOREDIT:
			if(GetDlgCtrlID((HWND)lParam) == nCtrlID) 
			{
				//SetBkMode((HDC)wParam, TRANSPARENT);
				SetBkMode((HDC)wParam, OPAQUE);
				return (INT_PTR)(HBRUSH)GetStockObject(DC_BRUSH);
			}

		case WM_COMMAND:
			if(LOWORD(wParam) == nCtrlID) 
			{
				if(HIWORD(wParam) == EN_SETFOCUS) 
				{
					SendMessage(hwnd,WM_COMMAND,MAKEWPARAM(nCtrlID, EN_CHANGE),(LPARAM)GetDlgItem(hwnd, nCtrlID));
				}
				else if(HIWORD(wParam) == EN_KILLFOCUS)
				{
					SendMessage(GetDlgItem(hwnd, nCtrlID),EM_HIDEBALLOONTIP,0,0);
				}
			}

		case WM_HELP:
			LPHELPINFO lphlp = (LPHELPINFO)lParam;
			if(wParam == 0 && lphlp != 0) 
			{
				if(GetDlgCtrlID((HWND)lphlp->hItemHandle) == nCtrlID) 
				{
					SendMessage(hwnd,WM_COMMAND,MAKEWPARAM(nCtrlID,EN_CHANGE),(LPARAM)GetDlgItem(hwnd, nCtrlID));
				}
			}
	}
	
	return CallWindowProc(oldstaticproc, hwnd, msg, wParam, lParam);
}


extern "C" __declspec(dllexport) void SubClassWindowProc(HWND hWnd,int nvarCtrlID)
{
	oldstaticproc = (WNDPROC)SetWindowLong(hWnd, GWL_WNDPROC, (LONG)StaticProc);
	nCtrlID = nvarCtrlID;
}