LXDE Forums

I start xpad each session automatically by a desktop entry in ~/.config/autostart
How can I make xpad to start minimized (not showing a window, just an icon in systray)?

You need to ask the application developer if they have an option to do this. There is no mechanism whatsoever to cause this in a general way.

Openbox can be set to start a particular application minimized (the formal term is "iconic"). If you want to play around with Openbox's XML rc file, the settings are documented at http://openbox.org/wiki/Help:Applications. If you'd prefer a GUI tool for making such settings, check out my own OBApps at http://obapps.sourceforge.net.

There is a big difference between Minimized/Iconic, which is a window manager concept, and An Icon in Systray, which arises from having special code to be an Xembed client.
I have no way of knowing which of these the original poster actually means.

If it's the latter, Alltray (http://alltray.trausch.us/) can probably do it.