Converting lines to solid shapes?

Hi all,
Just wondering if anybody knows how to do this....

I.E convert a line (with a wide stroke setting for example)
into an identical shape that is not defined as a line but rather a filled in (closed) shape whose extent is exactly the perimeter of the extent of the original stroke.....

I.E the same effect one would achieve if one were to manually trace around it.....(Thanks in advance.)

P.S can you also apply a gradient fill to an outline (probably not im guessing although i know this effect can be achieved with brushes)

Anyway im creating a new brush and I need some expert tricks if possible. anyway thanks in advance

Arrange>>Convert Line to Shape

arrange menu : convert line to shape will give you a shape the same size as your line - it will however, be a fill with no outline [so not exactly as it would be if you'd traced around it ;)] - if you add outline it will change dimensions accordingly

cannot give gradient to an outline - you would need to convert as above, first

Cheers!
I knew there should be such a function but had trouble finding it TY.