Yeah Autohotkey is extremely versatile. It could also replace a series of keypresses with "stuff", not just a normal hotkey like Ctrl-B.
So you could type b1 to rushbuy the first item in the planet queue and b2 to buy the second. Often I find a command string easier to memorise than a ton of unique hotkeys.
Now I can do all the things that used to KILL my deflicted wrist with the push of one of 12 special buttons on my gaming keyboard!
In GC many features are "mouse only" - especially anything related to buying/upgrading - so mouse macros are a godsend for the wrist.
The above loop is just the most basic example for "execute while key remains down". But it's a script language. You could run the loop 100 times flat or infinitely until stopped by the same or another key.
You can also limit the key to being "hot" only while the GC window has focus. But I was rusty on my leet scripting skeelz and forgot how that was done. I know I used that before. Sometime... 
That way those keys could have different functions for every application and your rushbuy (or whatever) macro wouldn't run if you hit the key while writing a forum post.
For the Rushbuy example I worked from the planetary screen because unlike on the global colony list, the click locations are static. That made it a lot easier. Also, refreshing the global colony list (300+ planets...) after every purchase creates noticable lag. "Next colony" creates none. So even if I only want to rushbuy the 10 "new" colonies, I may just weigh down the key and let it run through hundreds of colonies while leaving to get a mug of coffe.
So what? Doing boring and repetitive things is what computers were built for.
But scholar and gentleman? I'm rather a bit... stubborn. Okay, maybe upwards of 2 bits. That game designers consider the mouse the best and only interface to do something doesn't mean I have to agree. IMO, game designers are just people, not all-knowing gods. Merely disagreeing doesn't help me, though, so the interface has to change.
Sometimes it can be modded / scripted (like in X3) but at other times, only workarounds like Autohotkey will do. Either way, I don't easily take no for an answer.
And it is only a workaround unless you make the script really smart. For instance, AH can detect the colour of a certain pixel on the screen. And only if that pixel is of the colour for "button highlighted / buy available", execute the buy script.
This way one could program a heal bot for a generic MMORPG even if the executable was fortified and protected against tampering with it's memory regions. The script doesn't touch it's memory. It looks at the screen and the colour of the party's health bars...