 					viewport.scrollTop()
 
 				shouldLoadBottom = ->
+					#log "bottom pos #{builder.bottomDataPos()} < bottom visible #{bottomVisiblePos()} + padding #{bufferPadding()} "
 					!eof && builder.bottomDataPos() < bottomVisiblePos() + bufferPadding()
 
 				clipBottom = ->

						#log 'clipped off bottom ' + overage + ' bottom padding ' + builder.bottomPadding()

				shouldLoadTop = ->
					!bof && (builder.topDataPos() > topVisiblePos() - bufferPadding())

				clipTop = ->

						if toBePrepended.length
							bottomPos = builder.bottomDataPos()
							for wrapper in toBePrepended
								keepFetching = insertWrapperContent(wrapper) || keepFetching
								wrapper.op = 'none'

							heightIncrement = builder.bottomDataPos() - bottomPos

