If I add the "Hungary Standard" keyboard layout to the list of layouts in
gnome-keyboard-properties, then gnome-terminal interprets a control-z keypress
as if it were a control-minus keypress and zooms out (i.e. makes the font size
smaller) in the current terminal tab instead of breaking out of the currently
running process in that tab.

Control-minus still works to accomplish the same task, it's just that control-z
somehow turns into an alias for it, performing the "Zoom Out" action instead of
its normal function.

The problem occurs even if the currently-selected keyboard layout is set to the
default ("U.S. English").  The mere presence of the Hungarian layout on the list
of keyboard layouts is enough to cause this problem; Hungarian doesn't have to
actually be selected.

The problem doesn't occur if I reassign the keyboard shortcut for the Zoom Out
action to something other than control-minus.  For example, if I reassign it to
control-9, then control-z works properly again (and control-9 correctly zooms
out, while control-minus correctly does nothing).

The problem also doesn't occur in any application besides gnome-terminal.  For
example, if I type a control-z character in xterm, xterm properly breaks out of
the currently running process in the terminal window.  If I type a control-z
character in gedit, gedit correctly undoes the last action.

And if I type a control-z character in the ActiveState Komodo text editor after
enabling Komodo's "Enter Next Character as Raw Literal" mode, Komodo correctly
inserts a "SUB" character into the document I am currently editing.