Less than ten slots? No. Every power tray will have 10 slots. If you right click on the new tray, however, you'll be able to pick a configuration (and dragging them around near the edge can give you some interesting shapes as well.)
Edit: Like so:
(No, that is not my normal layout. :P )
...i kinda wanna play tetris now.
-STEELE =)
Allied to all sides so that no matter what, I'll come out on top!
Oh, and Crimson demands you play this arc-> Twisted Knives (MA Arc #397769)
If you only need three of the ten slots, you could slide the empty section of the tray under another window maybe.
Another thing you can do is create a Macro button that uses the Goto_tray command.
For a Force Fields Defender I have, the first tray is all attacks and a button labeled "Buff"
Hitting that button swaps Tray 1 to tray 9, which is Aid Other, the FF teammate bubbles and a button labelled "Attk" which swaps me back to tray 1.
I did a search for this but couldn't find an answer, so here goes:
Is there a way to have the additional power trays you can create (via the + symbol on the basic power trays) hold less than 10 powers? I'm trying to create just a small vertical power tray to put alongside the other two trays with only three powrs in it. Is there a way to do this?