Managed alternative to user32.dll FlashWindow

Question

In a .Net application that flashes the title bar and the corresponding taskbar button for a window, to attract the users' attention, P/Invoke code something like this is used:

[DllImport("user32.dll")]
private static extern bool FlashWindow(IntPtr hwnd, bool bInvert);

public static void FlashWindow(System.Windows.Forms.Form window)
{
  FlashWindow(window.Handle, false);
}

How can the same effect be triggered without using P/Invokes? Specifically, the .Net application is being updated to run fully on Linux/Mac OS X with Mono. Is there any way to construct a managed equivalent to FlashWindow or FlashWindowEx?

Answer 1

You should note that MicroSoft's own UI guidelines suggest that you should not do this unless the event really does require immediate attention.

Don't flash the taskbar button if the only thing the user has to do is activate the program, read a message, or see a change in status.

It is strongly advisable, even within a cross platform app, that the current system's UI guidelines are followed.
In this case it depends what you are trying to do but taking a guess:

• On Windows notification balloons are considered the best behaviour when used correctly.

• On OS X many applications use Growl. It appears someone may have done this via the cocoa-sharp project

• In Linux this will be very dependent on the underlying GUI framework, since GTK# is the preferred framework for mono here is the how they suggest you do it

If you really do want to do the equivalent of the Flashing window icon the equivalent on OS X would be a bouncing dock icon (Again, people don't like this). I don't know if that is wrapped by cocoa#.

In Linux the behaviour is again fragmented since many frameworks simply don't have the taskbar concept and you would be expected to play nicely with whatever framework you were in.

Answer 2

There is no managed equivalent for what you wish to do. Without getting into the debate of whether or not this is a good idea, a couple ideas come to mind, none of which are as elegant and simple as the FlashWindow call.

1. Use a timer to toggle the visibility of the form. This will have to effect of completely adding/removing the form from the task bar, but it will be noticed.

2. Use a timer to toggle the window state (minimized/normal) of the form. This will also get you noticed, but perhaps not in a good way.

3. Create a separate, blank form with ShowInTaskbar set to false and an opacity of 0. Then use a timer to alternately activate the blank form and the main form. This will have the effect of flashing the title bar of the main form, but will not effect the taskbar representation since another application is not gaining input focus.

DISCLAIMER: I have no idea how these will work on non-Windows OS'es, but am merely offering them up in the interest of managed alternatives.