Anatoly Lubarsky

Ever tried to flash a window using managed code ? The following method will flash the window title bar or the window taskbar button. Since there is no managed API available for this functionality - need to wrap a method imported from user32: FlashWindowEx:

[DllImport("user32.dll")]
static extern Int32 FlashWindowEx(ref FLASHWINFO pwfi);

Where FLASHWINFO struct is defined like so:

[StructLayout(LayoutKind.Sequential)]
public struct FLASHWINFO
{
    public UInt32 cbSize;
    public IntPtr hwnd;
    public Int32 dwFlags;
    public UInt32 uCount;
    public Int32 dwTimeout;
}

Where dwFlags can be one of the following:

// stop flashing
FLASHW_STOP = 0; 

// flash the window title 
FLASHW_CAPTION = 1; 

// flash the taskbar button
FLASHW_TRAY = 2; 

// 1 | 2
FLASHW_ALL = 3; 

// flash continuously 
FLASHW_TIMER = 4; 

// flash until the window comes to the foreground 
FLASHW_TIMERNOFG = 12; 

So the typical C# call will look like so:

public static bool Flash()
{
    FLASHWINFO fw = new FLASHWINFO();

    fw.cbSize = Convert.ToUInt32(Marshal.SizeOf(typeof(FLASHWINFO)));
    fw.hwnd = this.Handle;
    fw.dwFlags = 2;
    fw.uCount = UInt32.MaxValue;

    FlashWindowEx(ref fw);
}

See some other C# Win32 API tips and tricks. Enjoy :)

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