Let me just say this is the first time I've used a script program when I found Combat Mode, I quickly found some basic commands on AH's site and within 10 minutes I wrote this:
;PixelGetColor, OutputVar, X, Y
PixelGetColor,Color,644,1030 ; Return / Get the color of the pixel at the X and Y coordinates / at the X and Y location
If Color=0x00000B ; 0xFFFFFF is the color White, you need to modify this color to your desired color
SplashTextOn, , , In Range.
WinMove, In Range, , 700, 100
This gives me a message box saying In Range if the mob I'm targeting is in range, if not there's no box, simply by seeing if the red bar under my number 3 skill (Hunter's Shot) is present or not. (I ran a script someone else wrote to find the exact colour and co-ords of that box by clicking on it) Now this is very messy coding I'm sure, but it works and put together by a complete AutoHotkey noob, so I can see how this could easily lead to dangerous territory in more skilled hands and hence the reluctance to use it.