Echo Web Framework

Can anyone explain what should happen when a SelectField has just received focus and you press a key?
I've always assumed that it would

• jump to the first element in the list starting with the character
• jump to the next element in the list starting with subsequent key presses

However this doesn't always seem to be the case.

E.g, in the demo at http://demo.nextapp.com/echo3csjs/
under Core Components -> Basic Components there is a SelectField with values

• Africa
• Antarctica
• Asia
• Australia
• Europe
• North America
• South America

If you select it and press:

• 'a' it jumps to Antarctica. If you press 'a' repeatedly, it cycles through everything starting with 'A'. So far so good
• 'e' it jumps to Europe. If you press 'n' it then jumps to North America. If you press 's' it then jumps to 'South America'. Still good
• 'n' it jumps to North America. If you press 's' it doesn't jump to South America.
• 's' it jumps to South America. If you press 'a' it will jump back to Africa. If you press 'e' or 'n' nothing happens.

Colour me confused.

I've tried this with both echo2 and echo3, on Firefox 3 and IE 8.