it is just a cool feature suggestion to add some immersion, to add a hotkey it is easy, i saw this game was made probably in c++ since is made in ogre and have irrlicht sound lib
so do something like this:
switch (input){
case key_mouselock:
mouselocked=!mouselocked;
lookaround=mouselocked;
mouse.x=200;
mouse.y=200;
break;
case mouse_move:
if (!mouselocked) movepointer();
break;
case rightmouse:
if (!mouselocked) lookaround=!lookaround;
break;
}
(it took a while to color everything but it looks great at least)
as you can see i made like... all input things i said being handled here so its easier to understand what i mean ^^