code: private void build() {
  		if (list == -1) {
  			list = GL.glGenLists(1);
  			
  			SlickCallable.enterSafeBlock();
  			GL.glNewList(list, SGL.GL_COMPILE);
  			runnable.run();
  			GL.glEndList();
  			SlickCallable.leaveSafeBlock();
  		} else {
  			throw new RuntimeException("Attempt to build the display list more than once in CachedRender");
  		}
  	}
docs: Build the display list