usb-creator workflow is unintuitive

[Thibaut Brandscheid]

The usb-creator is kind of a semi public face of Ubuntu and an important tool to spread it. Therefore it should be as strait forward and simple to use as possible. To accomplish the goal of simplicity the usb-creator should automate as much tasks as possible for the user, prevent the user from making bad choices (installing an iso that is no longer updated) and require as less interaction (clicks) as possible.

The current workflow is for me often like this:
* search on the Internet an iso file and download it
* insert an usb stick
* format the usb stick clicking the 'Erase Disk' button
* click the 'Other' button of 'Source disc image' to add the newly downloaded iso to the list
* enlarge the usb-creator window to actually being able to see more than two entries in the 'Source disc image' list.
* selecting the desired iso
* change the 'When starting up...' setting option from 'Stored in reserved extra space' to 'Discard on shutdown...' (because the default often doesn't work).
* click 'Make Startup Disk' button
* enter the root password to allow the usb-creator to create an boot loader on the USB stick

The summary is, the list is way to long for such an important tool that allows the spreading of Ubuntu.

How it should be:
* insert an usb stick -> USB stick is automatically recognized.
* the user clicks on a button that allows him to download a new image from inside the usb-creator
* the user selects the OS and version to download (only important information is displayed)
* clicking on the 'Download image' button downloads the iso and adds it to the 'Source disc image' list. When downloading is done the sub-creator should close the download sub-page and highlight the downloaded image in the 'Source disc image' list.
* 'Make Startup USB' button should start the creation of the startup stick. If there is any data on the USB stick, ask the user if he is okay that the usb-creator formats the stick, else just go one and don't ask the user any more. Install the bootloader and what ever without asking the user.

This would represent the maximum steps a user would have to do to create a startup USB stick.

Mockup – usb-creator no iso file found:
http://ubuntuone.com/1BA81qfN7lCR25honhECqB

Mockup – download sub-page:
http://ubuntuone.com/36TJTQUE8VFxCJox9R45Xx

Mockup – main view – 'Source disc image' list widget:
http://ubuntuone.com/2DxwSmvd0dL3uJnA6Bohfh

PS: Proposal of usb creator UI update for vUDS trusty:
https://wiki.ubuntu.com/ubuntu-usb-startup-creator