(In reply to Catalin Sasca, Desktop Test Engineering [:csasca] from comment #13) > Ooh, that's how I recorded the first video, leaving via the window edge. But this is happening even with the mouse over the Fx window (leaving the sidebar on the right side), here's an [attachment](https://drive.google.com/file/d/1IzyikpAQ3Fv4q0mpzR1i_o5JnZZglaxS/view?usp=sharing) with it. Mousing out quickly towards the content area is due to bug 1957114. I think this is still a huge improvement from where it was because non-foregrounded windows were running into this a lot more frequently without this change. The browser essentially stops listening for `mousemove` events on macOS if the window isn't foregrounded, so we've added a `mouseout` event as well that _should_ fire when you mouse out of the sidebar, but we're getting inconsistent `x` position values for the `mouseout` event if the mouse out happens very quickly.
Bug 1956624 Comment 14 Edit History
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(In reply to Catalin Sasca, Desktop Test Engineering [:csasca] from comment #13) > Ooh, that's how I recorded the first video, leaving via the window edge. But this is happening even with the mouse over the Fx window (leaving the sidebar on the right side), here's an [attachment](https://drive.google.com/file/d/1IzyikpAQ3Fv4q0mpzR1i_o5JnZZglaxS/view?usp=sharing) with it. Mousing out quickly towards the content area is due to bug 1957114. I think this is still a huge improvement from where it was because non-foregrounded windows were running into this a lot more frequently without this change. The browser essentially stops listening for `mousemove` events on macOS if the window isn't foregrounded, so we've added a `mouseout` event as well that _should_ fire when you mouse out of the sidebar, but we're getting unexpected `x` position values for the `mouseout` event if the mouse out happens very quickly.