Here is a seventh beta test for Teensyduino 1.42.

The main new feature is a "Teensy" section in the Tools > Ports menu
which tries to show Teensy in all modes, not just Serial. New native
(no Java serial library) serial monitor code is also with these ports.

Old beta download links removed. Please use the latest version:

Changes since Teensyduino 1.42-beta6

Handle attempt to reopen serial port, clicking button while Arduino compiles
Windows: teensy_serialmon detect orphaned from Arduino IDE condition