Question

I have a dialog IDD_WINDOW_INFO that has to be opened when the user clicks a button or a menu item in my C++ Win32 application. The method that I use to open the dialog is in the following line:

DialogBox(hInstance, MAKEINTRESOURCE(IDD_WINDOW_INFO), hMainWindow, WindowInfoProc);

but my problem is that when that dialog box opens, the user cannot operate with the main window of my application. So what can I do to have both windows active?

Answer 1

You are calling DialogBox which shows the dialog modally. When a modal dialog is shown, the other owning windows are disabled and only the modal dialog can accept input. That is the very essence and intent of a modal dialog. The idea is that you can interact only with the dialog, and cannot interact with the other windows.

Another answer suggests passing NULL as the hWndParent parameter to DialogBox. That’s not the solution. That will result in you having an unowned window. Yes, you will be able to interact with the main window, but when you do so your main window will appear on top of the dialog. That’s because the ownership is set incorrectly. I recommend that you read about window ownership to better understand the issue.

The correct solution to your problem is to show a modeless dialog. A modeless dialog allows you to interact with the other windows in your application. And that’s exactly what you ask for in the question.

You show modeless dialogs by calling CreateDialog followed by ShowWindow. This MSDN article shows an example: Using Dialog Boxes.