Mar 18
Complete set of selection behaviors and shortcuts
You're missing these standard menu commands and shortcuts for multi-selection...
⌘A - Select all (in a given view, like inbox)
⌘⌥A - Deselect all
And you have ⌘-click for discontiguous selection, but are missing ⇧-click for contiguous (for example, select the first in the view, scroll down, ⇧-click on another to select everything in-between inclusive.)
Oh, and ⇧-Up/Down/Left/Right should extend the selection in the direction of the arrow pressed.
FWIW You can try all these behaviors in Finder, which uses them in a mostly standard way and many Mac users are familiar with.
Planned
You are right Timothy, thanks for the suggestions. These are actually on my todo list, but was not as high priority as other items. Now I've promoted them to higher priority.