In a World the mouse cursor is no longer centered, which frequently causes it to reach the edge of the screen. When this happens, the window abruptly snaps back to a different position.
Furthermore, when running in fullscreen mode on the secondary monitor, there is always a small white border that should not be there. Touching this border causes the game to either crash or minimizes the Minecraft window.
Thank you for your report!
We're tracking this issue in MCPE-230832, so this ticket is being resolved and linked as a duplicate.
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