Assembly の再コンパルを行わないようにロックします。
For example during drag operations you might want to prevent assembly reloading to not lose state during the drag.
Each LockReloadAssemblies must be matched by UnlockReloadAssemblies, otherwise scripts will never unload.
Unity automatically prevents reloading during mouse down.
関連項目: EditorApplication.UnlockReloadAssemblies.