[MlMt] Custom Key Binding for File -> Synchronize -> All Sources

[D Yates]

Does anybody know a way to create a custom key binding to File -> 
Synchronize -> All Sources?

I looked at http://manual.mailmate-app.com/key_binding_selectors, but 
could not find anything that looked appropriate.

I have switched all my mailboxes to synchronise once per hour, that way 
I am less likely to be distracted when new mail arrives. At times, I am 
expecting an email and wish to synchronise manually. I can do this via 
File -> Synchronize -> All Sources, but would really like a keyboard 
shortcut. Any ideas?

Many thanks,

Derek Yates