Hi,
I fixed this extremely annoying and partly game-breaking bug with a little workaround.
You need to edit the command_mapping_config.xml a little.
The file has two sections: <keyboard_control_settings> and <default_command_mapping>
In <keyboard_control_settings> there is an entry in group <group groupName="IDS_OTHERCONTROLS"> ,that I found commented out:
<!--<hotkey--> <!--name="IDS_FREE_CURSOR"--> <!--command="CMD_FREE_CURSOR" />-->
Uncomment this entry, so it looks exactly like this:
<hotkey name="IDS_FREE_CURSOR" command="CMD_FREE_CURSOR" />
When you do this, you get a new entry in the Control settings in-game, enabling you to set a new key to free the mouse pointer. Unfortunately, Control seems still to be reserved but you can use a key to your liking (^ in my case).
I thought, I can probably unassign Control if I remove the entry
<CMD_FREE_CURSOR keyCode="KEY_LCONTROL" />
from the other section in the file but it doesn't seem to work. LCONTROL always is reserved already when you go the in-game setting...
So, in general, the first section defines which key can be edited in the in-game settings, the second section has the assigned keys for those settings.
Make sure, you have a copy of the original file as always.
Let me know if it works for you, too.