I set a button named save ,when I click it the contents of the text input field are still there，I don't know if I save successfully,what should do?
Where textbox's input is saved ? In tinyDB , in an online database , in a list...Please provide more info or post a screenshot of your blocks
If saving to a File or other slow destination, there should be an event block that captures the completion of that process.
That would be a good place to empty out the textbox.Text to signal completion, if you will be asking for more.
Alternatively, use a Notifier.
It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.
To get an image of your blocks, right click in the Blocks Editor and select "Download Blocks as Image". You might want to use an image editor to crop etc. if required. Then post it here in the community.
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.