Legacy4J is currently incompatible with LEM and breaks multiple UI elements on LEM.
We are currently talking with the Legacy4J developers about this issue, and a solution is planned but it will take a significant amount of time to implement as a large amount of LEM’s UIs will need to be remade to make this possible.
Do not harass the Legacy4J or LEM team about this issue, both of them are very aware of it.
Currently known issues with using Legacy4J on LEM:
Chat box covering the host menu
UI elements in weird positions
UI elements failing to render
UI elements at incorrect scales
Incompatibility with LEM Client Helper
To anyone curious as to why this happens, its because LEM’s UI system was built around the expectation of the vanilla locations of UI elements. Legacy4J moves all of these UI elements in some way, causing the UI to look very broken.