By default, Maya's blendshape editor window orientation would be vertical. However, if you want it to be horizontal when it loads up back, this is the script:
Go to your Maya's Other Scripts directory, for example, C:\Program Files\Alias\Maya6.0\scripts\others, then find the file called createBlendShapePanelMenul.mel, edit it using whatever editor you would normally use, Notepad will do, find the following line : -
string $ma[] = `menuBarLayout -q -menuArray $panelControl`;
straight after on the next line, add this line : -
blendShapeMenuCmd $panel bseMIHoriz;
That's it, when you load Maya up now, Horizontal Layout will be the default layout.
kudos for Steven J Tubbrit.