Stonewall Attack: Horowitz Defence

Let's get some ideas/lines going on dealing with the Horowitz Defence:

Pawn to f4 is probably best for maintaing the stonewall structure. The knight can harass the bishop by going to B4. But the bishop drops back to e2 and the knight ends up wasting a tempo, once white can play pawn to c3. Or after pawn to f4, white plays bishop to e2 and exchanges bishops. Either way the position is about even.