Good idea, I tried adding accept_default="false", but it doesn't seem
to do anything (the first list entry is still picked, a bug regardless of
the search feature?).

Perhaps. We'll look into it.

Great - should I file an issue on bitbucket or will you after a little
investigation?

Hi Peter,

It turns out that accept_default is recognized only in very special cases and used for a particular purpose. I've removed it from the wiki for now since it's more of a undocumented/internal feature of Galaxy rather than something that useful to tool authors.

Currently my best workaround so far is to add a help attribute,
"When there are lots of entries, type here to search" (this needs
to be worded carefully as when there are only a few databases
setup you can't search).

Yes, this is in line with the label/tooltip solution. Additional suggestions
are welcome as well.

I think the option accept_default="false" would be fine (assuming
it did what we want it to do, and triggers the search text).