src/vs/workbench/contrib/comments/browser/commentsEditorContribution.ts/CommentController/onEditorMouseUp
class CommentController:	private onEditorMouseUp(e: IEditorMouseEvent): void {
		const matchedLineNumber = isMouseUpEventMatchMouseDown(this.mouseDownInfo, e);
		this.mouseDownInfo = null;

		if (matchedLineNumber === null || !e.target.element) {
			return;
		}

		if (e.target.element.className.indexOf('comment-diff-added') >= 0) {
			const lineNumber = e.target.position!.lineNumber;
			this.addOrToggleCommentAtLine(new Range(lineNumber, 1, lineNumber, 1), e);
		}
	}