FlashWindowEx function (winuser.h)

Flashes the specified window. It does not change the active state of the window.

BOOL FlashWindowEx(
  [in] PFLASHWINFO pfwi
);

[in] pfwi

A pointer to a FLASHWINFO structure.

The return value specifies the window's state before the call to the FlashWindowEx function. If the window caption was drawn as active before the call, the return value is nonzero. Otherwise, the return value is zero.

Typically, you flash a window to inform the user that the window requires attention but does not currently have the keyboard focus. When a window flashes, it appears to change from inactive to active status. An inactive caption bar changes to an active caption bar; an active caption bar changes to an inactive caption bar.

Error Handling Functions

FLASHWINFO

Notifying the User