Reflow and improve some comments., Switch to only tracking focus
events for disabling hotkeys.
The previous implementation depended on catching blur
events to
determine if a user left an input field so that hotkeys could be
reenabled. However, it turns out that those events will not be fired
if the focused element is destroyed. When a focused element is
destroyed, focus will change, causing another focus
event, so that
can be used to see what really happened.
Did involved introducing a new global variable, but really, that is
what setContext
is doing anyway, just hidden.
Closes #36.