In relation to the Original thread I thought I would show my date picker code which I made and intended to extend. It demonstrates some useful features and provides two date formats including the official TiddlyWiki serial date (at 12 noon). A time or dat/time picker can be created using the same method;
\define save-serial-date-actions() <$action-setfield $tiddler=<<tiddler>> $field=<<datename>> $value={{{ [all[current]get<html-date>split[-]join[]addsuffix[120000000]] }}}/>
\define set-date(datename:"touch" tiddler)
<$set name=datename value="$datename$-date">
<$set name=tiddler value="""$tiddler$""" emptyValue=<<currentTiddler>> >
<$set name=html-date filter="[<datename>addprefix[html-]]" >
<span title="set $datename$ date">
<$edit-text field=<<html-date>> type=date default=<<html-date>> inputActions=<<save-serial-date-actions>>/>
</span>
</$set></$set></$set>
\end
<<set-date>>
<<set-date journal>>