Gtk.Assistant.prototype.set_page_title
function set_page_title(page:Gtk.Widget, title:String):void {
    // Gjs wrapper for gtk_assistant_set_page_title()
}Sets a title for page.
The title is displayed in the header area of the assistant when page is the current page.
Since 2.10
- page
- a page of assistant 
- title
- the new title for page