Improvments can still be made.
First off, I don't see a speed cap for the balls.
Second, you might want to fix the little bug that causes me to lose my ball when it's falling straight down and I hit it with the tip of my paddle... if it IS a bug.
Third, you could've told the players that the game can be paused by pressing P.
Fourth, you could've provided a mute button for those who disliked the music, and maybe sounds for hitting each brick (with a way to mute those sounds).
Finally, on the level editor, why is it that you have to reselect the delete tool every time you remove a brick? It also seems a bit inaccurate, removing the wrong brick at times.