Hi guys.  I'm just starting out in SG and am trying to add a "loading dialog" or "progress dialog" while my category content is being fetched.  I'm using the Roku samples but in the old days it was easy to create a dialog message.  If anyone can offer me some guidance, it would be much appreciated.
The code from the Roku example to fetch the content is UriHandler.brs:

' ********** Copyright 2016 Roku Corp.  All Rights Reserved. **********
sub init()
  print "UriHandler.brs - [init]"
  m.port = createObject("roMessagePort")
  ' fields for checking if content has been loaded
  m.top.count = 0
  m.top.numRows = 0
  m.top.numRowsReceived = 0
  m.top.numBadRequests = 0
  m.top.contentSet = false
  ' Stores the content if not all requests are ready
  m.top.ContentCache = createObject("roSGNode", "ContentNode")
  m.top.Cache        = createObject("roSGNode", "Node")
  ' setting callbacks for url request and response
  m.top.observeField("request", m.port)
  m.top.observeField("encodeRequest", m.port)
  m.top.observeField("ContentCache", m.port)
  ' setting the task thread function
  m.top.functionName = "go"
  m.top.control = "RUN"
end sub
'Task function
sub go()
  print "UriHandler.brs - [go]"
  ' Holds requests by id
  m.jobsById = {}
 ' UriFetcher event loop
  while true
    msg = wait(0, m.port)
    mt = type(msg)
    print "--------------------------------------------------------------------------"
    print "Received event type '"; mt; "'"
    ' If a request was made
    if mt = "roSGNodeEvent"
      if msg.getField()="request"
        if addRequest(msg.getData()) <> true then print "Invalid request"
      else if msg.getField()="encodeRequest"
        if encodeRequest(msg.getData()) <> true then print "Invalid request"
      else if msg.getField()="ContentCache"
        updateContent()
      else
        print "Error: unrecognized field '"; msg.getField() ; "'"
      end if
    ' If a response was received
    else if mt="roUrlEvent"
      processResponse(msg)
    ' Handle unexpected cases
    else
    print "Error: unrecognized event type '"; mt ; "'"
    end if
  end while
end sub
' Encode the url and call addRequest
function encodeRequest(request as Object) as Boolean
  encoder = createObject("roUrlTransfer")
  encodedStr = encoder.escape(request.strToEncode)
  newParam = { uri: request.context.parameters.uri + encodedStr }
  request.context.parameters = newParam
  return addRequest(request)
end function
' @Params:
'   request: an AA containing a "context" node
'     Context node fields:
'      parameters: the request parameters: Headers, Method, and Url
'      num: the number related to the request
function addRequest(request as Object) as Boolean
  print "UriHandler.brs - [addRequest]"
  if type(request) = "roAssociativeArray"
    context = request.context
   if type(context) = "roSGNode"
      parameters = context.parameters
      if type(parameters)="roAssociativeArray"
        headers = parameters.headers
        method = parameters.method
       uri = parameters.uri
        if type(uri) = "roString"
          urlXfer = createObject("roUrlTransfer")
          urlXfer.SetCertificatesFile("common:/certs/ca-bundle.crt")
          urlXfer.InitClientCertificates()
          urlXfer.setUrl(uri)
          urlXfer.setPort(m.port)
          ' Add headers to the request
          for each header in headers
            urlXfer.AddHeader(header, headers.lookup(header))
          end for
          ' should transfer more stuff from parameters to urlXfer
          idKey = stri(urlXfer.getIdentity()).trim()
          'Make request based on request method
          ' AsyncGetToString returns false if the request couldn't be issued
          if method = "POST" or method = "PUT" or method = "DELETE"
            urlXfer.setRequest(method)
            ok = urlXfer.AsyncPostFromString("")
          else
            ok = urlXfer.AsyncGetToString()
          end if
          if ok then
            m.jobsById[idKey] = {
              context: request,
              xfer: urlXfer
            }
          else
            print "Error: request couldn't be issued"
          end if
        print "Initiating transfer '"; idkey; "' for URI '"; uri; "'"; " succeeded: "; ok
        else
          print "Error: invalid uri: "; uri
          m.top.numBadRequests++
     end if
      else
        print "Error: parameters is the wrong type: " + type(parameters)
        return false
      end if
   else
      print "Error: context is the wrong type: " + type(context)
    return false
   end if
  else
    print "Error: request is the wrong type: " + type(request)
    return false
  end if
  print "--------------------------------------------------------------------------"
  return true
end function
'Received a response
sub processResponse(msg as Object)
  print "UriHandler.brs - [processResponse]"
  idKey = stri(msg.GetSourceIdentity()).trim()
  job = m.jobsById[idKey]
print "IDKEY: "+idKey
  if job <> invalid
    context = job.context
    parameters = context.context.parameters
    jobnum = job.context.context.num
    uri = parameters.uri
    des = job.context.context.des
    print "Response for transfer '"; idkey; "' for URI '"; uri; "'";" ";des
    result = {
      code:    msg.GetResponseCode(),
      headers: msg.GetResponseHeaders(),
      content: msg.GetString(),
      num:     jobnum,
      des:     des
    }
    ' could handle various error codes, retry, etc. here
    m.jobsById.delete(idKey)
    job.context.context.response = result
    if msg.GetResponseCode() = 200
      if result.num = 3 or result.num = 4
        parseFollowedContent(job)
      else if result.num = 0
        parseResponse(job)
      else if result.num = 1
        parseLeaf(job)
      end if
    else if msg.GetResponseCode() = 204 and result.num = -7
      parseLogout(job)
    else if msg.GetResponseCode() = 204 and result.num = -10
      parseUnfollow(true)
    else
      if result.num > 0 and result.num < 3
        m.top.numBadRequests++
        m.top.numRowsReceived++
      else
        print "Error: status code was: " + (msg.GetResponseCode()).toStr()
      end if
    end if
  else
    print "Error: event for unknown job "; idkey
  end if
  print "--------------------------------------------------------------------------"
end sub
sub parseLeaf(job as object)
  print "UriHandler.brs - [parseLeaf]"
  result = job.context.context.response
  str = result.content
  num = result.num
  title = job.context.context.title
  xml = CreateObject("roXMLElement")
  if xml.parse(result.content)
    if xml.feed <> invalid
      row = CreateObject("roSGNode", "ContentNode")
      row.title = title
      for each element in xml.getChildElements()
        if element.getChildElements() <> invalid
          contentNode = CreateObject("roSGNode","ContentNode")
          contentNode.hdposterurl = [email="element@hdImg"]element@hdImg[/email]
          contentNode.sdposterurl = [email="element@sdImg"]element@sdImg[/email]
          for each child in element.getchildElements()
            if child.getname() = "title"
              contentNode.title = child.getText()
  'print "LEAF TITLE: "+contentNode.title
            else if child.getname() = "contentId"
              contentnode.episodeNumber = child.gettext()
            else if child.getname() = "genres"
              contentnode.categories = child.getText()
            else if child.getname() = "streamFormat"
              contentnode.streamFormat = child.gettext()
            'else if child.getname() = "contentQuality"
            'contentnode.contentQuality = child.gettext()
            else if child.getname() = "media"
              for each item in child.getchildElements()
                if item.getname() = "streamQuality"
                  contentnode.rating = item.gettext()
                else if item.getname() = "streamBitrate"
                  contentNode.maxBandWidth = item.gettext().toint()
                else if item.getname() = "streamUrl"
                  contentNode.url = item.gettext()
                else
                  'print "PARSING LEAF FOR: " ; item.getName() ; item.getText()
                end if
              end for
            else if child.getname() = "synopsis"
              contentnode.description = child.gettext()
            else if child.getname() = "genres"
              contentnode.shortdescriptionline1 = child.gettext()
            else if child.getname() = "runtime"
              contentnode.shortdescriptionline2 = child.gettext()
            end if
          end for
          row.appendChild(contentNode)

        end if
      end for
      print "ROW TITLE: "+row.title
      if m.top.contentcache.hasfield(m.top.numRowsReceived.tostr()) then m.top.numRowsReceived++
      contentAA = {}
      contentAA[m.top.numRowsReceived.toStr()] = row
      m.top.contentCache.addFields(contentAA)
     
    end if
  end if
end sub
' For loading category rowlist content
sub parseResponse(job as object)
  print "UriHandler.brs - [parseResponse]"
  result = job.context.context.response
  str = result.content
  num = result.num
  xml = CreateObject("roXMLElement")
  if xml.parse(result.content)
    if xml.category <> invalid
      if xml.category[0].GetName() = "category"
        print "begin category node parsing"
        categories = xml.GetChildElements()
        print "number of categories: " + categories.Count().toStr()
        contentRoot = CreateObject("roSGNode","ContentNode")
        contentRow = CreateObject("roSGNode","ContentNode")
        'Create a category node for each category'
        for each category in categories
          if category.getname() = "banner_ad"
            print "skipped banner_ad"
          else if category.getname() = "category"
            contentNode = CreateObject("roSGNode","ContentNode")
            print "category: " + [email="category@title"]category@title[/email] + " | " + [email="category@description"]category@description[/email]
            aa = {}
            aa.title = [email="category@title"]category@title[/email]
            aa.description = [email="category@description"]category@description[/email]
            aa.shortdescriptionline1 = [email="category@title"]category@title[/email]
            aa.shortdescriptionline2 = [email="category@description"]category@description[/email]
            aa.sdPosterUrl = [email="category@sd_img"]category@sd_img[/email]
            aa.hdposterurl = [email="category@hd_img"]category@hd_img[/email]
            m.count = 0
            categoryLeaves = category.getChildElements()
            for each leaf in categoryLeaves
              subAA = {}
              subAA.title = [email="leaf@title"]leaf@title[/email]
              subAA.url = [email="leaf@feed"]leaf@feed[/email]
       subAA.des = [email="leaf@description"]leaf@description[/email]
              a = {}
              a[subAA.title] = subAA
              AddAndSetFields(contentNode, a)
              m.count++
            end for
  
            AddAndSetFields(contentNode,{count: m.count})
            AddAndSetFields(contentNode, aa)
            contentRow.appendChild(contentNode)
          end if
        end for
        contentRoot.appendChild(contentRow)
        m.top.content = contentRoot
      end if
    end if
  end if
  print "done with parseResponse"
end sub

' Callback function for when content has finished parsing
sub updateContent()
  'screen = CreateObject("roSGScreen")
  'm.port = CreateObject("roMessagePort")
  'screen.setMessagePort(m.port)
  'scene = screen.CreateScene("ProgressDialogExample")
  'screen.show()
  'while(true)
    'msg = wait(0, m.port)
    'msgType = type(msg)
    'if msgType = "roSGScreenEvent"
      'if msg.isScreenClosed() then return
    'end if
  'end while
  print "UriHandler.brs - [updateContent]"
  if m.top.contentSet return
  if m.top.numRows - 1 = m.top.numRowsReceived
    parent = createObject("roSGNode", "ContentNode")
    newAA = {}
    newA=[]
    for i = (m.top.numRows - m.top.numCurrentRows) to m.top.numRowsReceived
    leaftitle = m.top.contentCache.getField(i.toStr()).title
     'print "UPDATE CONTENT: "+i.toStr()+" "+leaftitle+" "
 'add to array
     newAA.AddReplace(leaftitle,i.toStr())
      'parent.appendchild(m.top.contentCache.getField(i.toStr()))
    end for
newA.push(newAA)
newA.SortBy("key")
arr={}
for each arr in newA
for each item in arr.Items()
print "KEY: "+item.key +" VALUE: "+item.value
title=item.key
fieldname=item.value
newtitle = mid(title,6)
print "NEW TITLE: "+newtitle
m.top.contentCache.getField(fieldname.toStr()).title = newtitle
parent.appendchild(m.top.contentCache.getField(item.value))
end for
end for

    print "All content has finished loading"
    m.top.contentSet = true
    m.top.categorycontent = parent
    itemToCache = {}
    itemToCache[m.top.category] = parent
    AddAndSetFields(m.top.cache, itemToCache)
  else
    print "Not all content has finished loading yet"
  end if
end sub

The component UriHandler.xml is:

<?xml version="1.0" encoding="utf-8" ?>
<!-- Copyright 2016 Roku Corp.  All Rights Reserved. -->
<component name="UriHandler" extends="Task">
  <interface>
    <!-- Field to issue a request to the handler -->
   <field id="request" type="assocarray"/>
    <!-- Issue a request to encode to the handler (contains top game content) -->
    <field id="encodeRequest" type="assocarray"/>
    <!-- Contains main menu content -->
    <field id="content" type="node"/>
    <field id="categorycontent" type="node"/>
    <field id="count" type="integer"/>
    <!-- The # of rows to populate -->
    <field id="numRows" type="integer"/>
    <!-- # of rows of content received -->
    <field id="numRowsReceived" type="integer"/>
    <!-- # of requests that have bad/no content -->
    <field id="numBadRequests" type="integer" value="0"/>
    <field id="numCurrentRows" type="integer" value="0"/>
    <!-- variable so updateContent only runs once -->
    <field id="contentSet" type="boolean"/>
    <!-- Caching content removes redundant url requests -->
    <field id="ContentCache" type="node"/>
    <field id="Cache"        type="node"/>
    <!-- Field to store category tag for the current content item -->
    <field id="Category"     type="string"/>
  </interface>
  <script type="text/brightscript" uri="pkg:/components/SGHelperFunctions.brs"/>
  <script type="text/brightscript" uri="pkg:/components/UriHandler.brs"/>
</component>

And lastly, the component for the progressdialogscene.xml is:

<?xml version = "1.0" encoding = "utf-8" ?>
<!--********** Copyright 2016 Roku Corp.  All Rights Reserved. **********-->
<component name = "ProgressDialogExample" extends = "Scene" >
  <script type = "text/brightscript" >
    <![CDATA[
    sub init()
      'm.top.backgroundURI = "pkg:/images/rsgde_bg_hd.jpg"
      'example = m.top.findNode("instructLabel")
      'examplerect = example.boundingRect()
      'centerx = (1280 - examplerect.width) / 2
      'centery = (720 - examplerect.height) / 2
      'example.translation = [ centerx, centery ]
      m.top.setFocus(true)
      showdialog()
    end sub
    sub showdialog()
      progressdialog = createObject("roSGNode", "ProgressDialog")
      'progressdialog.backgroundUri = "pkg:/images/rsgde_dlg_bg_hd.9.png"
      progressdialog.title = "Please wait...loading"
      m.top.dialog = progressdialog
      m.timer = createObject("RoSGNode", "Timer")
      m.timer.duration = 5
      m.timer.control = "start"
      m.timer.ObserveField("fire", "dismissdialog")
    end sub
    sub dismissdialog()
      m.top.dialog.close = true
    end sub
    function onKeyEvent(key as String, press as Boolean) as Boolean
      if press then
        'if key = "OK"
         'dismissdialog()
          'return true
        'end if
      end if
      return false
    end function
    ]]>
  </script>
  <children >
  </children>
</component>

I was trying to create a screen with the progressidalogscene in updateContent() sub of UriHandler.brs and the screen seems to open ok but when I tried closing it with screen.close(), the screen goes black or shows the main category list.  I'm thinking the roSGScreen I'm creating for the progress dialog is screwing up the roSGScreen that is supposed to display the category content (leafs, etc).  Can anyone help me clue me in on how to add a loader/progress dialog that will automatically close once content is loaded?  Thanks.