What would need to happen is that while you're typing you can open up

the completion panel, but keep on typing.

Escape would banish the panel

Up and down would move the selection in the completion list

and insert the rest of what you're typing

and select it

right would banish the list and keep the currently selected completion

etc...

Is that at all doable?

You can not update the TextMate editor when running a command or plug-in,

in other words typing in TextMate to reduce the list of completion is

currently impossible. What you could do is move the typing to an external

textfield that would in turn reduce the list of completions. To me

personally that is not worth investing time and effort in, since I would

imagine that it would be difficult not to disrupt the flow of editing when

suddenly your typing is thrown into a different editing context. I  think

Allan is planning on adding shrink-list-as-you-type-completion in TM2.0.

Joachim Mårtensson