I also had high hopes that iMacFusion 5.0.3 would fix this annoying mouse behavior that was *not* an issue in earlier Fusion versions (<4.0).
To be specific: iMAC's Fusion 5.0.3 locks the mouse cursor into the Fusion window
and a Ctrl+Alt key action is needed to release the mouse back to the iMac screen.
The current behavior is like a vSphere console window and not very suitable for a Fusion window.
Please provide focus to every window that the mouse moves into like in the old X11 days or make it a user setting,
without the requirement to release the mouse out of the Fusion window.
-Thanks.