since i (for the x'th time) blew up 40 banes instead of morphing some additional ones in my ling/bling control group, i decided to fix the grid hotkey setup.
i searched on the forums here, and i found some people who complained about the same problem but found no answer, so i decided to open this short "guide" to save others some time.
Here's how it's done: (short version, just unbind key)
1. in SC2, add a custom key layout in Hotkeys, name it (e.g. "banes")
2. in windows filesystem search for your Account profile, there is a folder "Hotkeys"
(in windows 7 its in C:\Users\<you>\Documents\StarCraft II\Accounts\<########>\Hotkeys)
3. edit file "banes.SC2Hotkeys", add line below [Commands]:
[Commands]
Explode/Baneling=
(extended version)
4. add another custom key layout in SC2, from standard keys, unbind / rebind any skill you like, and save to banes2
5. check the "banes2.SC2Hotkeys" file in your Hotkey folder.
[Commands] will now have additional skills that you can just c&p to your banes.SC2Hotkeys
Hope i helped at least one of you;)