src/vs/base/browser/ui/inputbox/inputBox.ts/InputBox/insertAtCursor
class InputBox:	public insertAtCursor(text: string): void {
		const inputElement = this.inputElement;
		const start = inputElement.selectionStart;
		const end = inputElement.selectionEnd;
		const content = inputElement.value;

		if (start !== null && end !== null) {
			this.value = content.substr(0, start) + text + content.substr(end);
			inputElement.setSelectionRange(start + 1, start + 1);
			this.layout();
		}
	}