Window should remain with the same size, to avoid it hiding its bottom behind
the desktop bottom toolbar. This is due to the creation of the tabs at the top
of the terminal subwindows when one has first MANUALLY resized the
gnome-terminal window to occupy the full available desktop area. Opening a new
terminal (when you only had one before) creates tabs that "pushes" the window
further down. This is not a great problem, but when your command line get hidden
behind the desktop bottom tool bar after a CTRL+SHIFT+T one nead to resize it to
see what you type at the bottom of the shell window. We would just need to do
something like "substracting" the tabs height to the effective terminal
subwindow height to get the whole window  remain with the same height it had before.

Other information:
When the windows is maximized using the top right corner button or the ALT+F10
keyshortcut. This little problem do not occur and window do not expand under the
toolbar. So I can imagine there is no big difficulty to extend the behaviour to
the case where window has been resized manually. Anyway we can continue using
this latter technic to avoid this problem !