Mouse cursor is not centered when opening a new gui, while the in-game cursor is centered, though it moves to the mouse position once the mouse is moved. If the left mouse button is clicked before moving to the actual position, it will actually click in the centered position.
[media]
Seems as if it is the same bug as MCPE-15796
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We're tracking this issue in MC-263682, so this ticket is being resolved and linked as a duplicate.
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