Ctrl+pgup, Ctrl+pgdown key bindings are not usable in OpenBSD

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The default tab switching bindings to not appear to work on OpenBSD. I tried to rebind them using "set keybinding", but the dialog seems unable to capture these key sequences. I was however able to bind "ctrl+right" and "ctrl+left" just fine.

Odd.

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I tried this on my work machine and the bindings here do work. In summary:

Thinkpad x61 - Ctrl+pgup/pgdown do not work
Dell Optiplex - Fine.

I expect the thinkpad keyboard sends something slightly different. It is worth noting that shift+pgup works in an xterm on both machines.