Comment 3 for bug 1520819

I analyzed this further.
As the changes to data/ui/login.glade and src/client/accounts/add-edit-page.vala do not result to any gtk-criticals when applied to r < 1891 I took a closer look at r1891.
The first four critical errors above result from Gtk.Button trash_delete being declared a second time as a local variable so that the instance variable private Gtk.Button trash_delete is not used.
The last critical error comes from mail being installed locally and therefore can be ignored.
This branch has a second commit that addresses the crtitical errors.

So the patch to split up the account creation / edit dialog into a Gtk.Notebook should be ready for review :)

The Gtk.Notebook introduces a new label. As I do not know how translations are handled for elementary os it is not contained in the po-Files so far.
Is it the correct way to add the label there?