[Ubiquity] Prepare Partitions doesn't guide user, not intuitive

Binary package hint: ubiquity

When a user first sees "Prepare Partitions" (as it works in Feisty Herd4), the user might think that all they need to do is select (highlight) the "free space" and click Forward to have Feisty installed there. There is no warning or informational feedback at the time that the user clicks the "Forward" button that indicates that the user didn't take any action.

How to reproduce:

Launch LiveCD Installer,
At "Prepare Disk Space", select "Manual" and then click the Forward button.
At "Prepare Partitions", select "free space" (assuming disk has free space on it) then click the Forward button.
User is brought to next step, "Step 7 of 8" ("Who are you?"), without any feedback that there were no partition changes made.

There is, however, a bit of direction given at the bottom of the window that reads:
  "Make sure to allocate space for a root partition ("/"), with a minimum size of 2GB, and a swap partition of at least 256MB."
  However, at least one user (myself) thought that by selecting the "free space" I was actually specifying where to create a partition.

There isn't a severe problem as the "no action taken" condition is caught a bit later... after the user begins the install from Step 8 of 8 ("Ready to install"), if no partition was marked as the root partition an error message is displayed and the user can start over.

A quick fix might be to simply check if any partition was added or changed during the "Prepare Partitions" step. If user clicked the Forward button without making changes, then it is probably safe to assume they didn't realize that they were supposed to use that screen to create and/or format the partition they want to install into (and then to mark it as the root ("/") mount point). A message box telling the user that no changes were made, "Continue, / Go Back", would probably help. (Re-thinking the user-interface on this a little would be even better ... ).