[TxMt] How to: set reg-exp on by default?

Hi, simple question I think, but I can't find the answer I quasi-always use regular expressions in the find and replace box, but this button defaults to plain text search.

Q: What is the pref called to set this button's default to ticked?

Executing "defaults read com.macromates.textmate"

The closest I can see is this

OakFindPanelOptions = { action = replaceAll; findInProjectIgnoreCase = 0; findString = "duchaine"; ignoreCase = 1; replaceAllScope = document; replaceString = " $1"; wrapAround = 0; };

But no sign of "Regular Expression"

Tim