Mnemonics interfere with alternate keys
Submitted by John Ralls
Assigned to gtk-quartz maintainers
gtkwindow.c hard-codes priv->mnemonic_modifier = GDK_MOD1_MASK. This captures Alt-key events and prevents the entry of alternate keys on Macs.
Bug 663856 fixed this for accelerators; similar magic needs to be applied for mnemonics as well.