As other users have already pointed out, what you are trying to acheive will not work - at least not as expected and definitely not cross browser. It's also good to search before posting here. I found several links, however ultimately settled on a year old post on this website.
Ultimately, you cannot sendkeys
at this level so either you need to create something similar to some of the links suggested by other users in the linked thread, or as @michaelb958 suggested, have the user manually hit Ctrl+F.