This mod fixes MC-301281, which caused sprint and sneak toggle states to be reset whenever a GUI was opened. This meant that if you have sprint or sneak toggled on, and you open a chest/chat/menu, your sprint and sneak would be toggled off after closing the GUI.

This bug was caused by Mojang's fix for MC-300695 only accounting for keyboard keys, not mouse buttons. The game would incorrectly reset toggle states for any keybind assigned to a mouse button when opening screens, even though mouse buttons don't have the same key-release behavior that caused the original issue.