"Delete" already has a keyboard binding, it's just impossible to find on the UI -- see bug 398355.
"Insert new subtask" already has "Ctrl-Shift-N" as a keyboard binding, which matches well with the HIG (see http://library.gnome.org/devel/hig-book/stable/input-keyboard.html.en#standard-shortcuts).
"Delete" already has a keyboard binding, it's just impossible to find on the UI -- see bug 398355.
"Insert new subtask" already has "Ctrl-Shift-N" as a keyboard binding, which matches well with the HIG (see http:// library. gnome.org/ devel/hig- book/stable/ input-keyboard. html.en# standard- shortcuts).