Question

VC6.0编写的对话框无法关闭

我知道把//CDialog::OnCancel();的//去掉后，“取消”按钮会不起作用，但没想到这个窗口无论是点击右上角的X号，或alt+F4也都关不了。难道这句代码除了影响“取消”按钮，还会影响那个X号？

Answer 1

在这里，OnCancel()函数和其它的按钮响应函数不太一样，它本身是CDialog类的虚函数。在基于对话框的程序中，点击关闭按钮，按键 ALT + F4，都会调用此函数（可加断点调试查看），注释掉调用基类函数的代码自然会导致无法手动关闭对话框。

可以查阅MSDN:
CDialog::OnCancel
virtual void OnCancel( );
If you implement the Cancel button in a modeless dialog box, you must
override the OnCancel method and call DestroyWindow from within
it. Do not call the base-class method, because it calls EndDialog, which
makes the dialog box invisible but does not destroy it.

追问

OK

Answer 2

　　在基于对话框的程序中，点击关闭按钮，按键 ALT + F4，都会调用此函数（可加断点调试查看），注释掉调用基类函数的代码自然会导致无法手动关闭对话框。
　　可以查阅MSDN:
　　CDialog::OnCancel
　　virtual void OnCancel( );
　　If you implement the Cancel button in a modeless dialog box, you must override the OnCancel method and call DestroyWindow from within it. Do not call the base-class method, because it calls EndDialog, which makes the dialog box invisible but does not destroy it.