Just checked it. Pressing 'C' on top of ladder (Actions: [C]limb) still shows up search bar, but U/D/Q for "Climb [U]p or [D]own? (or [q]uit)" does not.
The game already does call preventDefault for events it handles. If it doesn't know what to do with the key, it bubbles the event up, which is the correct behavior. This is not a bug in my game, it's the option you've set in your browser.
