If you try to shut down Windows, and there’s a program that is not allowing the shutdown to proceed, then the Blocked Shutdown Resolver (BSDR) shows a list of windows that includes the one that is processing the shutdown notification, as well as the windows who are waiting for their turn to process the shutdown notification. For each window, the information looks like this:

The program controls all the parts of the presentation. The description comes from the window title. The icon come from the window icon. And the subtitle comes from the string that the program passed to the Shutdown­Block­Reason­Create function.

If the program did not call Shutdown­Block­Reason­Create, then a generic system-provided string is used like “This app is preventing shutdown” or “This app is preventing you from restarting.”

But why is the description sometimes blank? Who would create a window with no title?

Programs often create windows that they never intend to show to the user. It might be a helper window that exists to receive messages or to act as an anchor for positioning another window. Since the program knew that the window would never be shown to the user, it didn’t bother giving it a title.

Except that the Blocked Shutdown Resolver shows the title.

And if the title is empty, you get a blank string.

So, programmers, give your windows useful titles, even the ones you never thought would be shown to the user.