I was just playing around with things, and I modified one of @omz's gists to allow infinite scroll. I noticed when more colors are added at the bottom, sometimes the scrollbar disappears and doesn't come back even when I scroll again. I'm using this code:

import ui
from random import randint
import console
import clipboard
# Generate some random hex colors:

colors = ['#%X%X%X' % (randint(0,255), randint(0,255), randint(0,255)) for i in xrange(50)]
offset = 0
class SVDelegate (object):  
    def scrollview_did_scroll(self, sv):
        scroll = sv.content_offset[1]
        #how far you can scroll before hitting the bottom
        maxscroll = 0
        for sub in sv.subviews:
            maxscroll += sub.height
        sv.content_size = 0, maxscroll
        #see if user is within 500 pixels of end of scroll
        if scroll > maxscroll-sv.height-500:
            print 'change'
            colors2 = ['#%X%X%X'%(randint(0,255),randint(0,255),randint(0,255)) for i in xrange(50)]
            for i, c in enumerate(colors2):
                swatch = ui.Button(frame=(0, i*80+maxscroll, 400, 80), background_color=c)
                swatch.flex = 'w'
                swatch.action = tapped
                sv.add_subview(swatch)

#Add buttons for all the colors to a scroll view:
scroll_view = ui.ScrollView(frame=(0, 0, 400, 480))
scroll_view.content_size = (0, len(colors) * 80)
scroll_view.delegate = SVDelegate()

def tapped(sender):
    r, g, b, a = sender.background_color
    hex_color = '#%X%X%X' % (int(r*255), int(g*255), int(b*255))
    clipboard.set(hex_color)
    console.hud_alert(hex_color + ' copied')


for i, c in enumerate(colors):
    swatch = ui.Button(frame=(0, i*80, 400, 80), background_color=c)
    swatch.flex = 'w'
    swatch.action = tapped
    scroll_view.add_subview(swatch)
scroll_view.name = 'Random Color Picker'
scroll_view.present('sheet')

Can anyone else replicate this behavior?