The Expand command labels elements on the page with letters to allow them to be selected by pressing that key.
Right now, the map key tags are generated from this:
var keys = 'dsawgvcxlohnmzbptuy'.split('')
If a user set the key H to the expand command, there is ambiguity as to whether the element tagged with an h should be selected or the Expand command should be run again. The best solution seems to be to remove hotkeys from the list of available map key tags.