System-Modal Window

An application can designate a system-modal window: a window that receives all keyboard and mouse input, effectively disabling all other windows. The user must respond to the system-modal window before continuing work in other windows. An application sets and clears the system-modal window by using the WinSetSysModalWindow function.

Because system-modal windows have absolute control of input, you must be careful when using them in your applications. Ideally, an application uses a system-modal window only when there is danger of losing data if the user does not respond to a problem immediately.

Although an application can destroy a system-modal window, the new active window then becomes a system-modal window. An application can make another window active while the first system-modal window exists. But again, the new active window will become the system-modal window. In general, once a system-modal window is set, it continues to exist in the PM session until the application explicitly clears it.