When i bind the 搂 key via guake preferences it works during the session but when i shutdown/log out and log back in again a popup appears and tells me that a problem occurred while binding the 搂 key and that i will have to bind another one.
It's the top left key with 搂 and 陆 on it. (This is on a Swedish keyboard) http://ascii-table.com/img/keyboard-153.png
My keymap is sv-latin1
Sadly, it is keybinder that handle this part. I also have some key I cannot bind, fortunately, [ 虏 ] on French keyboard (same position as your [ 搂 ] works on Ubuntu 16)
Using Ubuntu 16.04, I can bind the 搂 key (Guake 0.8.4).
But it won't work with Ubuntu 17.10 (I got a popup telling me that a problem occurred too).
I am using the Swiss-French keyboard layout. Keycode is 41
I found a workaround:

Note that if I assign the key "搂" it works but then if I press the letter "s", it open guake as well. This is probably a gnome related bug. And that's why I choose "Shift 搂".
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I found a workaround:
Note that if I assign the key "搂" it works but then if I press the letter "s", it open guake as well. This is probably a gnome related bug. And that's why I choose "Shift 搂".