long										prevNum;
bool										enteringNewNum = true;
long delegate(long a, long b)	curOp;


void onDigit(int d) {
	auto lab = Label(`.main.display`);

	char[] text;
	if (enteringNewNum || "0" == lab.text) {
		text = "" ~ cast(char)(d + '0');
		enteringNewNum = false;
	} else {
		text = lab.text ~ cast(char)(d + '0');
	}

	char[] convText = to!(char[])(to!(long)(text));
	if (convText == text) {
		lab.text = text;
	}
}