I am wondering about the name of this movie. It was made in the late 80's or early 90's.

I forget what it was about except for one scene. In the scene, the main character (a boy) goes into a library (I think) with the ceiling painted. Until about right here the movie is not animated. At one point the ceiling starts dripping paint all over and the boy is sent into an animated world. That's all I remember. Can anyone help me?

Your answers may be found in this extensive thread:

https://www.askmehelpdesk.com/movies/animated-movie-mid-90s-101881.html

Yep, Definitely "The Pagemaster" The link Purukivel provided for you has many details about the movie.