Show {expr} inside the balloon. For the GUI {expr} is used as a string. For a terminal {expr} can be a list, which contains the lines of the balloon. If {expr} is not a list it will be split with |balloon_split()|. If {expr} is an empty string any existing balloon is removed. Example: func GetBalloonContent() " ... initiate getting the content return '' endfunc set balloonexpr=GetBalloonContent() func BalloonCallback(result) call balloon_show(a:result) endfunc Can also be used as a |method|: GetText()->balloon_show() The intended use is that fetching the content of the balloon is initiated from 'balloonexpr'. It will invoke an asynchronous method, in which a callback invokes balloon_show(). The 'balloonexpr' itself can return an empty string or a placeholder. When showing a balloon is not possible nothing happens, no error message. {only available when compiled with the |+balloon_eval| or |+balloon_eval_term| feature}