A week ago, I've migrated code to OGRE 1.2RC1 from 1.0.x Overall, it came through without blocks, but with a few rough spots here and there.
First of all, crosshair does not appear anymore in Linux, but it appears in Windows builds. This remain untackled for now.
Second, mouse control is wacky on Linux. For some reason Ogre::InputManager::getMouseRelativeX() returns large numbers from time to time. Maybe something changed. I'll take a look at OGRE demos to see if anything different has appeared in them with mouse control.
Big thanks to OGRE team for awesome open-source 3D engine.