Hi,
thank you very much for your bug report.

I've looked into this issue and this seems to be a bug in Unity's editor GUI code (on Linux). I've been able to reproduce this issue with a few simple lines of code and have reported this issue to Unity. I'm keeping my fingers crossed that they fix this (within a reasonable time frame). Unfortunately there is nothing else I can do to address this issue for now (from within UMotion's code).

Please let me know in case you have any follow-up questions.

Best regards,
Peter

Thank you for your reply.

I understand this issue caused by Unity.

I also hope they fix this issue.