I dont know how you can do it with jQuery resizable
but this is actually pretty easy stuff to do with a custom code. Here is a FIDDLE that i made with no trouble. Of course it's not 100% ready to go but with a little more work you can use it anyway you like.
The idea is you add a div
with 0px width
and 1px border
as a seperator between your main divs
. Define some global vars
to check current mouse pos and mouse down/up operations and simply with mousemove
reduce the size of divs
at the left and rigth side of the seperator accordingly. Check the fiddle. I beleieve it's not too complicated. I can explain anything if you need.