The 'clickEvent' is un-clickable if Multiplayer links are off.
This should be fixed as there is no way to open a website using this method and people get confused as to why it doesnt work.

command:

/tellraw @a {
 text:"Click.",
 clickEvent:{
 action:run_command,
 value:"/say Clicked."
 }
}

Esc, options, multiplayer settings, prompt links