Allow handler to determine how it was invoked

[rouilj]

Right now the handler function doesn't get any argument. Would it be possible to have the handler
get information about how it was invoked. The use case is to allow the user to search for recent pages
that were accessed.

If the user hit enter or clicked on the entry the selected page from the command menu replaces the current page.
If he user crtl+click or ctlr+entered to select the page from command-pal, the page would be opened in a new
window/tab instead.