I did get the textbox to stretch to 100% if I set the style:
and have the textbox within a div set to absolue with top and bottom set to 0. However, the table has to be set to relative. This doesn't work if there is a row above and below the textbox row like the following table:
It appears that having a relative object within a table cell set to 100% doesn't work nicely. Is there any other workarounds?