C# Signature:

[DllImport("user32.dll")]
static extern Int16 FlashWindowEx(ref FLASHWINFO pwfi);

User-Defined Types:

[StructLayout(LayoutKind.Sequential)]
public struct FLASHWINFO
{
    public UInt32 cbSize;
    public IntPtr hwnd;
    public UInt32 dwFlags;
    public UInt32 uCount;
    public UInt32 dwTimeout;
}

Notes:

//Stop flashing. The system restores the window to its original state.
public const UInt32 FLASHW_STOP = 0;
//Flash the window caption.
public const UInt32 FLASHW_CAPTION = 1;
//Flash the taskbar button.
public const UInt32 FLASHW_TRAY = 2;
//Flash both the window caption and taskbar button.
//This is equivalent to setting the FLASHW_CAPTION | FLASHW_TRAY flags.
public const UInt32 FLASHW_ALL = 3;
//Flash continuously, until the FLASHW_STOP flag is set.
public const UInt32 FLASHW_TIMER = 4;
//Flash continuously until the window comes to the foreground.
public const UInt32 FLASHW_TIMERNOFG = 12;

Tips & Tricks:

Please add some!

Sample Code:

/// <summary>
/// Flashes a window
/// </summary>
/// <param name="hWnd">The handle to the window to flash</param>
/// <returns>whether or not the window needed flashing</returns>
public static bool FlashWindowEx(IntPtr hWnd)
{
    FLASHWINFO fInfo = new FLASHWINFO();

    fInfo.cbSize = (uint)Marshal.SizeOf(fInfo);
    fInfo.hwnd = hWnd;
    fInfo.dwFlags = FLASHW_ALL;
    fInfo.uCount = UInt32.MaxValue;
    fInfo.dwTimeout = 0;

    return (FlashWindowEx(ref fInfo) == 0);
}

...

if (!FlashWindowEx(someForm.Handle))
{
    //The window was already active
}

Alternative Managed API:

Do you know one? Please contribute it!

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).