Drives and letter templates on desktop

Google Drive and OneDrive on desktop

Opening from and saving to Google Drive or OneDrive works as in the browser while you are connected. Two differences:

A result made by the desktop app's own offline engine has no Save to … button; the result says "Files made on this device can't be saved to a cloud drive from here. Download them instead."
An editor export made only on your device is first added to your File Library and synced, then saved to the drive. If the library can't sync right then, you'll see "Your library hasn't synced yet — cloud saving works once it has. Try again in a moment."

Letter templates work offline too (see Utilities & Nepal, "On the desktop app", for every message):

Templates you have opened before, the workspace letterhead and its logo stay on this computer, so you can fill in letters and Print them offline. Download PDF and Save to library need the online engine.
You can create and change your own templates offline; they are saved on this computer and go to your workspace the next time you are online.
If a change you made offline can't go onto the template when you reconnect — someone else changed it, it was deleted, or you can no longer change it — it is kept as a new template of your own called "(my changes)". Nothing is lost.
Workspace templates can't be changed offline, and a new template needs one check online that you may create templates.
Your unsaved work in the template builder is kept on this computer as a draft while you are offline, and goes to your account when you reconnect — so another computer offers it too. A draft of a template that was deleted meanwhile goes with it; one of a template you may no longer change stays on this computer.