@ robiandi: I didn't forget, I just hadn't programmed the check for "more than 1 word in the line" very well (I tend to follow the convention of using commas and having spaces after them, so it's hard to notice some things - I'll fix it for the next version).
@ PhiLho: I'm not checking labels against a list of commands, I'm checking the line doesn't have more than one word in it (i.e. a space in the middle) or a comma (the flexibility of the AHK syntax becomes a pain for this sort of matching

), but your suggestion made me realise it would be a lot simpler if I crop off the spaces at the start of the line and then check for spaces.
@ toralf: I thought about doing that too (I've had docking of windows in my Alt-Tab replacement for some months - but the code was necessarily a lot more complicated). I might look into it some time if there is demand. Another possibility might be attaching a small window into the PSPad window somewhere like with the taskbar clock script with meters (which should then work without any timers and be more responsive, but just depends if PSPad plays nicely with that method or not).