A Dash 8 Captain reported overshooting assigned altitude on climb; citing an overly complex altitude pre-select interface on the autopilot as contributing.

Narrative

After departure from YUM airport we received a clearance to climb to 15;000 FT. We received a handoff to ABQ Center at approximately 14;300 FT. After checking on with ABQ our attention was diverted for a few moments and the aircraft climbed through our pre-selected altitude to approximately 16;300 FT. We recognized the error and immediately corrected back to 15;000 FT. ABQ Center recognized our mistake and verified our assigned altitude and that we were correcting. The DHC-8 has an altitude pre-select and an ALT SEL button located on the FCP. You must always set a new altitude in the altitude pre-select window and also select the ALT SEL button on the FCP. This 2 step requirement can make it easier to make a mistake. Also the FCP is very small with each button in close proximity. It is very easy to unintentionally de-select the ALT SEL button when arming another mode such as NAV or HDG (etc). All of this can be guarded against by making the ID-802 a large part of your scan as it makes you aware of the modes you have armed. Both I and my First Officer recall seeing the ALT SEL mode selected several times during our climb. I believe the most likely thing that happened is that it was inadvertently de-selected when we intercepted the airway on the departure just after checking on with ABQ Center and only moments before reaching 15;000 FT. I believe that the most common sense correction to this situation is a modification to the aircraft to allow for the pilot to select and altitude in the altitude pre-select window and that is the altitude the aircraft will next capture.