Add HTTP API to main menu (#9998)

builtin/fstk/dialog.lua

@@ -67,3 +67,22 @@ function dialog_create(name,get_formspec,buttonhandler,eventhandler)
 	ui.add(self)
 	return self
 end
+
+function messagebox(name, message)
+	return dialog_create(name,
+			function()
+				return ([[
+					formspec_version[3]
+					size[8,3]
+					textarea[0.375,0.375;7.25,1.2;;;%s]
+					button[3,1.825;2,0.8;ok;%s]
+				]]):format(message, fgettext("OK"))
+			end,
+			function(this, fields)
+				if fields.ok then
+					this:delete()
+					return true
+				end
+			end,
+			nil)
+end