As I’m temporarily on OS X while my laptop is being repaired, I run into one of my OS X gripes, which is that Command-M does something deeply useless: it minimizes the current window, with no way to undo the action with the keyboard (that I know of).
This is a real problem when using thunderbird, as those are the keys I’m used to typing to start a new email (the default configuration for Thunderbird on OS X has Command-Shift-M as the appropriate keybinding).
I found my salvation thanks to the keyconfig extension, which lets you configure shortcuts. There are a few things wrong with the UI for that tool, but after a few false starts I got it to do what I wanted. Me happy.
Now if only Thunderbird let me store my Junk Mail data on the server or in the cloud, that would make me that much happier.