Priority

Context: I'm using a Linux based system for work. I prefer the simple interface provided by GNOME Geary. A such I notcied a lack of any feature to set the priority of a message which can be very important with Outlook web clients for Office365 accounts.

I decided to implement the missing feature in my free time.

This work is intended to bring a priority menu to the mail composer in order to allow sending mails with high, normal or low importance.

• Implement Priority and Importance headers from RFC2156
• Implement X-Priority to allow Outlook clients to properly identify the message as high, normal or low priority

I may try to bring priority support to the actual mail list in a later work.

Note: This is my first time writing Vala code.

EDIT 30/12/2020: Added notification for high importance to conversation-message UI

EDIT 31/12/2020: Added notification for high importance to conversation list

I don't know why but randomly a crash occurs in GLib:

![crt] 14:48:09.0976 GLib:Did not see expected message GLib-GObject-WARNING **: g_object_weak_unref: couldn't find weak ref *

Could this be a crash caused by a bug in the Vala to C translator? Could this be a bug in GLib?

I would have liked to get a debug log but unfortunatly it is not possible when the application is started by GNOME Builder. And the application does not run outside of GNOME Builder as it asks for some weird library name that exists nowhere (libstemmer.so.0)

EDIT 09/01/2021: The crash I observed is not a bug in Vala translator or GLib it's apparenlty related to an issue in libhandy. For more information please refer to line 937-944 in application-client.vala (https://gitlab.gnome.org/Yuri6037/geary/-/blob/mainline/src/client/application/application-client.vala)