When ever i click on edit control and combo box area dialog box get close.

#include <windows.h>
#include "resource.h"

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

BOOL    CALLBACK AddRuleDlgProc (HWND, UINT, WPARAM, LPARAM) ;

void AddRule(HWND hAddRuleDlg);


int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("HelloWin") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;

     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = MAKEINTRESOURCE(IDR_MENU1);
     wndclass.lpszClassName = szAppName ;

     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("This program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName,                  // window class name
                          TEXT ("The Hello Program"), // window caption
                          WS_OVERLAPPEDWINDOW,        // window style
                          CW_USEDEFAULT,              // initial x position
                          CW_USEDEFAULT,              // initial y position
                          CW_USEDEFAULT,              // initial x size
                          CW_USEDEFAULT,              // initial y size
                          NULL,                       // parent window handle
                          NULL,                       // window menu handle
                          hInstance,                  // program instance handle
                          NULL) ;                     // creation parameters
     
     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;
     
     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     HDC         hdc ;
     PAINTSTRUCT ps ;
     RECT        rect ;
     
	 static HINSTANCE hInstance ;    
     HMENU      hMenu ;

     switch (message)
     {
     case WM_CREATE:
	  hInstance = ((LPCREATESTRUCT) lParam)->hInstance ;
          return 0 ;
          

	  
     case WM_COMMAND:
          hMenu = GetMenu (hwnd) ;
          
          switch (LOWORD (wParam))
          {
                       
          case ID_FILE_EXIT:
               SendMessage (hwnd, WM_CLOSE, 0, 0) ;
               return 0 ;
               
          case ID_TOOL:
			   DialogBox (hInstance, MAKEINTRESOURCE(IDD_DIALOG1), hwnd, AddRuleDlgProc) ;            
			   break;
          }
          break ; 
	 case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}


// Dailag Box for Adding Rules
BOOL CALLBACK AddRuleDlgProc (HWND hAddRuleDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	 static int lPort,rPort;
	 static TCHAR ipLocAddr[40],ipRemAddr[40],ipLocMask[40],ipRemMask[40];
	 
	 switch (message)
     {
     case WM_INITDIALOG :
		   //AddRule(hAddRuleDlg);
		    return TRUE ;

     case WM_COMMAND :
          switch (LOWORD (wParam))
          {
          case IDOK :
			   GetDlgItemText(hAddRuleDlg,IDC_EDIT1,ipLocAddr,40);
			   
          case IDCLOSE :
               EndDialog (hAddRuleDlg, 0);
               return TRUE ;
          }

	 case WM_CLOSE:

		 EndDialog(hAddRuleDlg,0);
		  return TRUE ;
          break ;
     }
     return FALSE ;
}