Method setCustomBox

src/webpage/markdown.ts:1108–1113

(
		stringToHTML: (arg1: string) => HTMLElement,
		HTMLToString = MarkDown.gatherBoxText.bind(MarkDown),
	)

				this.txt = boxText.split("");
				box.append(this.makeHTML({keep: true}));
				const len = txti.length + txt.length;
				text = boxText;

				this.boxupdate(len, false, 0);
			} else {
				this.txt = txt.split("");
				box.innerHTML = "";
				box.append(this.makeHTML({keep: true}));
				text = txt;