GUI appearance and GNOME

[S P L I C E R]

Hi! I've been programming Mac OS X apps for just over a year now. I'm 
thinking of buying a laptop and running RedHat Linux on it.

On the GNUstep.org web site, the following is stated about GNOME:
"GNUstep works with GNOME and KDE, although it has not been optimized 
to do so (no one has put in the work to do that). GNUstep runs on top 
of X11."

What does this mean exactly? If I write an app using GNUstep, what will 
it look like under GNOME? Will its windows/buttons etc take on the look 
of the current gnome theme (such as RedHat's BlueCurve)? What about X11 
themes?