I don't think I *HAVE* to write external taskbar program. KDE for instance has taskbar/panel functionality built-in directly into plasma which manages also desktop icons, etc.
What I need are commands to retrieve icons of currently running programs as TPicture and functions to manage systray.
Also my DE is supposed to look and feel like Haiku, something like XPDE (google it) which resembles exactly Windows XP, though my DE will resemble Haiku, so no customization other than it is possible in Haiku.