Desktop notifications on Windows hangs colcon command

[Ace314159]

With the default parameters, after a colcon build finishes, the powershell window gets stuck on Summary: 1 package finished for a couple of seconds before giving control back to the user.

I noticed this was because of the time.sleep(5) on Line 90 here:

colcon-notification/colcon_notification/desktop_notification/win32.py

Lines 78 to 92 in 5401d06

	try:
	win32gui.Shell_NotifyIcon(
	win32gui.NIM_ADD, nid)
	win32gui.Shell_NotifyIcon(
	win32gui.NIM_MODIFY, (
	hwnd, 0, win32gui.NIF_INFO, win32con.WM_USER + 20, hicon,
	'Balloon tooltip', message, 200, title))
	except Exception as e: # noqa: F841
	logger.debug(
	'Failed to show the notification: {e}'.format_map(locals()))
	else:
	# wait a while before destroying the window
	time.sleep(5)
	finally:
	win32gui.DestroyWindow(hwnd)

Is there a reason to destroy the window? I commented out the line that destroys the window and the notification disappeared after a couple of seconds, and nothing seemed to go wrong.

If destroying the window is required, would it be possible to do this without having the sleep?

[cottsay]

This is maybe a bit nuanced, but my understanding is that the message that appears in the notification center (and hangs around for a couple of seconds) is only part of the story here. The entity that creates that notification is a tray icon, and if you drop the sleep, it won't hang around for very long. The popup notification on Windows 10/11 seems to be shown for a few seconds regardless.

We should probably understand why this is the way that it is, probably by checking the behavior on older Windows versions. If it is indeed required, I'd like to consider spawning a subprocess to display the notification and then exit rather than holding the colcon process hostage.