Document all keyboard shortcuts
In issue #260 (closed), I asked to add a keyboard shortcut to focus the mail search bar. Turns out there already is one -- technically a "mnemonic" -- and so the ticket was closed. But the original source of confusion was that this shortcut is nonobvious and undocumented.
In many GNOME applications, you can see a list of keyboard shortcuts by going to the Top bar app menu > Keyboard shortcuts. I've seen it enough in other GNOME apps that this is where I thought to look first. The closest thing in Evolution is a link to the GNOME Help documents and this doesn't list the shortcut to focus the search bar. I also looked through the menu-bar menus, as functions there often show the keyboard shortcut next to them, if there is one.
The only indication of the search shortcut (Alt+C, at least in my locale), is when you hold down the Alt key, the c in "Search" is underlined. I don't think I've ever seen this sort of Alt key mnemonic used in other apps for anything other than the menu bar itself, though, and underlining one letter is not a super obvious indication, if one doesn't know to look for it. There's a whole row of buttons in between the menu bar and Search (Send/Receive, Forward, Reply) which do not have Alt key mnemonics, so you'd have to look closely further down the window before noticing the mnemonics for Search.
I think it would be helpful if this "mnemonic" shortcut and other Alt key combinations were documented in the GNOME Help pages for Evolution, and maybe also if the shortcut was displayed next to the related items in the menu bar pop-outs.