How to implement popup message dialog

[AlannY <m alanny ru>]

Hi.

So, picture:

+---------------------------------+
|   Desktop                       |
|             +-------------------+
|             |   popup window    |
|             |                   |
|-------------+-------+-----------+
|       taskbar       | * | clock |
+---------------------+-----------+

I want to realize that amazing popup window, like I see it in X-Chat,
Pidgin, GMPC etc.

I mean, small window (popup) near clock. Without header (close button
and so on). Which popups in several seconds and then hides.

How to implement it with best way? Using GTK+.