I was customizing my UI, and then I found theses weird bugs:
1. If I hide any buttons in the "Sculpt Tree > Right click menu on the layer", the buttons that I have hidden in the layer Right click menu will disappear and cannot be un-hide in UI customizing mode.
2. If I hide any options in the gizmo modes switching drop-down list for Pose tool, after closing and restarting Customize UI mode, it will disappear and cannot be un-hide.
Other buttons in 3DCoat works well and can be easily un-hide.
Currently, I can only fix this by restoring my workspace, thank you!