Sometimes, when getting re-routed a lot, or dodging storms, or on an especially complex approach during turbulence, I have wished for a separate set of buttons on the panel to select autopilot lateral and vertical mode (HDG, GNAV, ENAV, VS, IAS, etc.), instead of having to click the knob and push-scroll for the desired mode, and then exit. Interacting with the MFD buttons can be problematic in bump air. A separate sub-panel could even look like an STEC AP box

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Cheers,
Byron