<p>I was playing a bit with Windows Vista (still using XP) and I liked how the standard Control Panel worked. Do you think this design is good also for normal applications?</p>

<p>I like the idea of showing main topics with large fonts + icons. Details within each main topic are displayed using a small font and are immediatelly accessible without the need to browse the menu. Probably everybody knows Vista, but anyway, <a href="http://www.computerperformance.co.uk/images/Vista/control_panel2.jpg" rel="nofollow noreferrer">here</a> is the Control Panel layout.</p>

<p>Compared to a classic layout of icons for main topics and menu for minor topics, the Control Panel GUI seems to be good at first sight.</p>

<p>I haven't seen any app using this kind of GUI, so I don't know if I should rather use the common approach with icons and menu for a common application? Maybe this Control Panel GUI is suitable only for setting some options, other than working with any data?</p>

Wouldn't the session number tell you this ?
ProcessIdToSessionId (GetCurrentProcessId(),&dwSessionNum)
You'd have to check the OS version as well, using GetVersionEx: for everything up to XP/Server 2003 session 0 is local (service or interactive console), anything higher is virtual. For Vista/2008 session 0 and 1 are both local (0 is service, 1 is console), everything else is virtual.
I'm guessing your Delphi units would declare the session number as var, so you wouldn't need the ampersand.