如果把 fileName 的定义放到函数里, GetFileName对话框就出不来了.
char fileName[1024];
LRESULT CALLBACK HandleCommands(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
OPENFILENAME ofn;
memset(&ofn, 0, sizeof(ofn));
ofn.lStructSize = sizeof (ofn);
ofn.hwndOwner = hWnd;
ofn.hInstance = hInst;
ofn.lpstrFilter = "Text Source File(*.txt)\0*.txt\0";

ofn.lpstrCustomFilter = (LPTSTR)NULL;
ofn.nMaxCustFilter = 0L;
ofn.nFilterIndex = 2L;
ofn.lpstrFile = fileName;
ofn.nMaxFile = 1024;

ofn.lpstrFileTitle = NULL;
ofn.nMaxFileTitle = 0;
ofn.lpstrInitialDir = ".";
ofn.lpstrTitle = "Open Script";
ofn.nFileOffset = 0;
ofn.nFileExtension = 0;
ofn.lpstrDefExt = "*.dump";
ofn.lCustData = 0;

GetOpenFileName(&ofn);
}