+1 on that.
Not only in the Test Window variable list, but in all grids.
I'm hesitating on having it back on the right if data is right-aligned, but if it can't be like that, I'd accept having it always on the left, instead of always on the right.
I'd even consider having all those drop-down buttons (like on the type picker in the variable list or date-time picker on any date-typed columns) on the left too.