Look inside and change the language to 「日本語」「にほんご」「한국어」 then the start-flag and tabs could not be clicked after that.
This is a test project about specific location of block-comment breaks layout of the editor. When the location of a block-comment too low from the highest script, the start/stop and tabs were hidden by menus. This problem is found only in the language 「日本語」「にほんご」「한국어」. at 2018/01/08; MacOS 10.13; Google Chrome 71.0.3578.98