Currently not but it is something I could keep in mind.
Would you have a button to expand it permanently or everytime you want to pick a brick?

Hmm....

Maybe a check box on the brick window (maybe next to the brick list popup menu or the Bricklink) that says "Expand [ ] 1 row [ ] 2 row [ ] 3 row".

or have an option to show it as a vertical box on the left side of the screen that is 3 columns wide. (or again, have it able to expand 1 2 or 3 columns)

As for permanently or everytime you pick a brick, you can have a check box on the window that says "[ ] AutoResize", which will detect your mouse moving near the bottom 1 row of brick, then expands if it hovers over a brick for 1 sec or half sec or whatever you feel like is right.

Or, if nobody wants to use that, having just a shortcut key to scroll through the brick list would be fine too. Mouse scroll, arrow keys, page up/down keys, , and . keys, [ and ] keys....... 😄