# Disable all key sequences for widget named in variable hWnd, except
# the cursor navigation keys (regardless of the state ctrl/shift/etc.)
# and Ctrl-C (Copy to Clipboard).

bind $hWnd <KeyPress> {
    switch -- %K {
        "Up" -
        "Left" -
        "Right" -
        "Down" -
        "Next" -
        "Prior" -
        "Home" -
        "End" {
        }

        "c" -
        "C" {
            if {(%s & 0x04) == 0} {
                break
            }
        }

        default {
            break
        }
    }
}

# Addendum: also a good idea disable the cut and paste events.

bind $hWnd <<Paste>> "break"
bind $hWnd <<Cut>> "break"