Active windows are almost always indicated in some graphical way, but not that distinct that you would be able to tell the active window in a split second. And that is how fast you would like to, wouldn't you?
Here is a AutoHotKey script for you. Activate it by ctrl+super+space and toggle with super+alt+space.
; This script puts a red border on the current window. ; Nice to have something clearly indicating what is active. ; Author: @danielgasinski ; Source of inspiration http://blog.sveri.de/2010/01/27/script-to-draw-a-border-around-an-active-window-with-autohotkey/ Toggle:=0 ^#space:: Loop { if(Toggle != 1) { b = 6 ; border full_width = 1936 ; w value from WinGetPos, lite more than screen width WinGetPos, x, y, w, h, A if(w >= full_width) { b:=12 ; We make the border thicker when in full screen, otherwise it may not be visible } width:=w-b height:=h-b Gui, -Caption +Lastfound +AlwaysOnTop +Toolwindow Gui, Color, FF0000 WinSet, Region, %b%-%b% %b%-%height% %width%-%height% %width%-%b% %b%-%b% 0-0 %w%-0 %w%-%h% 0-%h% 0-0 Gui, Show, w%w% h%h% x%x% y%y% NoActivate, } Sleep, 50 ; Chance/time to interupt } return ; Toggle on of alt+win+space !#space:: Toggle := Toggle<1 ? 1 : 0 Gui, Show, w0 h0 x0 y0 NoActivate, returnExample of how the script works. Nota bene: ignore the semicolons on row 18 and 39. It is something fishy with the AutoHotKey highlight script making them appear in the post. Sorry.