It's one of the powerfull things in debian: alternatives.
/usr/bin/x-terminal-emulator links to /etc/alternatives/x-terminal-emulator.
/etc/alternatives/x-terminal-emulator points to the x-terminal-emulator you have choosen (by modifiying this link)
If you want to modify the alternatives for x-terminal-emulator, try this:
Code:
update-alternatives --config x-terminal-emulator
Apps that call directly /usr/bin/gnome-terminal.wrapper won't change.
The ones who call /usr/bin/x-terminal-emulator will now launch the one you have choosen by this double link mechanism.