I am not sure if this is the right place for this post, but couldn't find a natural choice.
Just in case someone would like to disable the button which hides definitively the header (Hero is probably the right name) in the first page, I found this solution :
In \vendor\flarum\core\js\forum\dist\app.js :
babelHelpers.createClass(WelcomeHero, [{
key: 'init',
value: function init() {
/*this.hidden = localStorage.getItem('welcomeHidden');*/
this.hidden = false
}
},
Which means : Comment the existing line : this.hidden...
And replace by : this.hidden = false
Then, if you click the button, the header disappears. But just reload your page, it is present again.
It is useful if you want to place some image there, and would like it to stay.
There is surely a better way to do it, but I couldn't find on the forum.