src/vs/editor/contrib/message/messageController.ts/MessageWidget/constructor
class MessageWidget:	constructor(editor: ICodeEditor, { lineNumber, column }: IPosition, text: string) {

		this._editor = editor;
		this._editor.revealLinesInCenterIfOutsideViewport(lineNumber, lineNumber, ScrollType.Smooth);
		this._position = { lineNumber, column: column - 1 };

		this._domNode = document.createElement('div');
		this._domNode.classList.add('monaco-editor-overlaymessage');

		const anchorTop = document.createElement('div');
		anchorTop.classList.add('anchor', 'top');
		this._domNode.appendChild(anchorTop);

		const message = document.createElement('div');
		message.classList.add('message');
		message.textContent = text;
		this._domNode.appendChild(message);

		const anchorBottom = document.createElement('div');
		anchorBottom.classList.add('anchor', 'below');
		this._domNode.appendChild(anchorBottom);

		this._editor.addContentWidget(this);
		this._domNode.classList.add('fadeIn');
	}