The mouse pointer still moves under the window when playing on Windows, both in fullscreen and windowed mode. It does not leave the screen to other monitors, as it did on 1.21.121.
The pointer moves with every mouse movement, resulting in various positions across the screen when opening the invetory, interacting with a container or when opening the game menu.
Pointer position should be centered either in the center of the screen, or center of the invetory / container.
To replicate this issue:
start playing the game either in fullscreen or windowed mode
do several mouse movements in one direction while in the first person mode (crosshair in the middle of the screen)
open inventory and check the position of the cursor
close inventory and do several mouse movements in different direction
open inventory (or game menu) and check the (completely different) position now
rinse and repeat
We are still tracking this issue at MCPE-230832.