Sliding up the inbox list when new mails arrive

Bug summary

When the inbox list is at the top and the user receives new mails, please keep the list at the top (i.e. sliding it upwards).

About you

• Geary version: 0.12.3
• Installation method: Flathub
• Your desktop: GNOME
• Your operating system and version: Fedora 28 SB
• Email provider: Posteo, Gmail, own

Steps to reproduce

1. Scroll inbox to the top
2. Get new mail
3. Inbox isn’t at the top anymore