Quote:
how to change behaviour of standard Linux login window?
I am not really sure what you mean by that: Linux has no "login window".
Linux (like UNIXes, to which it is quite similar) has a "login" process. Whenever a terminal becomes free, this login process will start a session there and present a (text-based) login/password prompt.
What you perhaps mean by "login window" is the following: many graphical environments (GNOME, KDE, ....) don't deem it reasonable that the user uses the described login process and then start whatever graphical environment he wants. They basically intercept the login process and replace it with their own graphical version of it. Search for "gdm" (graphical display manager) for a detailed descrition of how this works.
This doesn't mean you have to use it, though. you can still trigger the native login process and use it to log in a user at the system. You will probably make use of "udev"-rules: "udev" is a kernel driver that constantly scans the system for changes in hardware. If you, for instance, put in a CD into the CD-ROM-drive and you get a nice symbol on your desktop, this is (ultimately)
udev at work. udev works from a rule-set which basically states "if this and this happens execute this list of actions".
I hope this helps.
bakunin