Takes the frontmost window, maximises it vertically, and centres it horizontally if it was off-screen

Smart Maximize.applescript

tell application "Finder"
	set {dx1, dy1, dx2, dy2} to bounds of window of desktop
end tell

set cur_app to (path to frontmost application as Unicode text)

tell application cur_app
	set {x1, y1, x2, y2} to bounds of front window
	if x1 < dx1 or x2 > dx2 then
		set displayWidth to dx2 - dx1
		set windowWidth to x2 - x1
		set padWidth to (displayWidth - windowWidth) / 2
		set x1 to dx1 + padWidth
		set x2 to dx2 - padWidth
	end if
	tell front window
		set bounds to {x1, dy1, x2, dy2}
	end tell
end tell