When you open the boss checklist, there are four buttons near its top-left area, for toggling some things in the list. But when you close the boss checklist, those buttons seem to be "hid" rather than removed, meaning that there's still a "click" sound for mousing over the area with the buttons, as well as a "bloop" sound for clicking on the invisible buttons.
Not only that, but clicking on the buttons does affect the boss checklist the next time that you open it, and you can even hide bosses by Alt-clicking on an invisible boss name (though you only seem to be able to hide up to one boss per time that the boss checklist is closed).
The scrollbar is mostly unaffected by this. It does not make a "click" sound and can not be moved with the left mouse button while the checklist is hidden, but it still gets moved if the scroll wheel is scrolled up or down in the checklist's area.
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Note that this does not happen immediately after rebooting Terraria (I don't know about after reloading mods), until that the boss checklist is opened at least once while in-game, though it does persist when leaving a world and entering a new one without rebooting Terraria.
When you open the boss checklist, there are four buttons near its top-left area, for toggling some things in the list. But when you close the boss checklist, those buttons seem to be "hid" rather than removed, meaning that there's still a "click" sound for mousing over the area with the buttons, as well as a "bloop" sound for clicking on the invisible buttons.
Not only that, but clicking on the buttons does affect the boss checklist the next time that you open it, and you can even hide bosses by Alt-clicking on an invisible boss name (though you only seem to be able to hide up to one boss per time that the boss checklist is closed).
The scrollbar is mostly unaffected by this. It does not make a "click" sound and can not be moved with the left mouse button while the checklist is hidden, but it still gets moved if the scroll wheel is scrolled up or down in the checklist's area.
~
Note that this does not happen immediately after rebooting Terraria (I don't know about after reloading mods), until that the boss checklist is opened at least once while in-game, though it does persist when leaving a world and entering a new one without rebooting Terraria.