HTML Attributes for <SELECT ...>
onFocus ="script command(s)"
onBlur ="script command(s)"

Usage Recommendation
Use it, but don't rely on it.

onFocus and onBlur for onFocus work identically as for <INPUT onFocus="...">, so we won't dwell on them long. Let us just reiterate that the most common use for these events, that of changing the status bar, is generally annoying and is a bad idea. 

<SELECT
 NAME="size"
onFocus = "window.status='What Size Pizza?'"
 onBlur = "window.status=window.defaultStatus"
 >
<OPTION VALUE="s">small
<OPTION VALUE="m">medium
<OPTION VALUE="l">large
</SELECT>

which gives us

pizza size:
phone number:

(Form is not live)

<OPTION ...> >