The dialog informs:
  There are unsaved modifications to your XXX account.
  You are about to select another account, which will discard your changes.

And asks a question:
   Are you sure you want to proceed?

Buttons: Cancel and Discard.

Problems:
- the questions requires a YES/NO answer, buttons indicate some actions
- "cancel" and "discard" have very similar meanings. This creates multiple problems:
  - non-native English speakers with limited English knowledge won't be able to easily differentiate between the two
  - some languages (e.g. Romanian) use the same word to translate both words.
  - discard (a button that makes the user loose information) is default




I suggest switching the "Discard" button to "Discard profile changes", and default button focus to "Cancel".


Also, I believe this violates the HIG (question must be bold and first thing in the dialog): http://library.gnome.org/devel/hig-book/2.91/windows-
alert.html.en#alerts-confirmation


If indeed the HIG is violated, suggested rewording:

   Are you sure you want to discard changes made to your XXX account?

   You have selected another account. By switching to that account, you will lose all changes make to your XXX account.

Buttons: Cancel (default focus), Discard profile changes.