timerPlus

An improved version of my "timer" program I made for the AP Computer Science Principles exam. I've added bug-fixing code that would've bloated my program too much to use for the exam. 

Fixes:
Can't input any number in the beginning besides 1 (preset timer) and 2 (custom timer)
Preset timer - Can't input an option besides the preset options
Custom timer - Can't input negative numbers, and decimal numbers will be rounded, to avoid the time counting down forever
Timer won't say "time's up" after error message.

Added:
Date and time in top left corner