Task Coach is an offline todo or task list management tool. It is available for Ubuntu, other Linux distros and even Android. It just saves a single
.tsk XML file that you can place in your Dropbox for access across multiple computer and devices.
To install in Ubuntu:
$ sudo add-apt-repository https://launchpad.net/~taskcoach-developers/+archive/ppa $ sudo apt-get update $ sudo apt install taskcoach
Tried with: Task Coach 1.3.36 and Ubuntu 14.04