gistfile1.txt

(*
 * Before running following codes, this script has to be allowed assistive access.
 * System Preferences -> Security & Privacy -> Privacy -> Accessibility
 *)

tell application "Finder"
	set desktopBounds to bounds of window of desktop
	set desktopWidth to item 3 of desktopBounds
	set desktopHeight to item 4 of desktopBounds
end tell

tell application "System Events"
	set process1 to item 1 of (every process whose frontmost is true)
	tell process1
		set window1 to item 1 of (every window whose subrole is "AXStandardWindow")
		set position of window1 to {0, 0}
		set size of window1 to {desktopWidth / 2, desktopHeight}
	end tell
end tell