Visualize long pmap process using Gtk.ProgressBarLeaf

Hey all,
I was wondering if it is possible to view the progress of the pmap function using GtkProgressBar when pmap is running on multiple (or all) processes.

using Distributed, Statistics
id = addprocs()
@everywhere begin
    using Gtk, Images
    global base_id = myid()
    global cnt = 0
btn = GtkButton("Open directory")
ent = GtkEntry()
pb = GtkProgressBar()
grid = GtkGrid()
grid[1,1] = btn
grid[1:5,2] = ent
grid[1:5,3] = pb

@everywhere function ImageHeight(name, arr_length)
    img = load(name)
    sz = size(img)
    ratio = cnt / arr_length
    global cnt += 1
    return sz[1]

b = WorkerPool(workers()[2:end])
signal_connect(btn, "clicked") do widget   
    dir = open_dialog("Select Image Folder", action=GtkFileChooserAction.SELECT_FOLDER)
    dir = dir.*"\\"
    @async begin
        lst = readdir(dir)
        len = length(lst)
        hh = pmap(ImageHeight, b, dir.*lst, len)
        aver = mean(hh)
        remotecall_fetch(set_gtk_property!, base_id, ent, :text, "Average height of images: $aver")

# see
@everywhere function update_gtkprogressbar(frac::AbstractFloat)
    Gtk.GLib.g_idle_add(nothing) do update_ui
        remotecall_fetch(set_gtk_property!, base_id, pb, :fraction, frac)
        Cint(false) # MUST HAVE, MUST BE FALSE

win = GtkWindow(grid, "Get height of images", 500, 200)

You can see that I have a problem updating the Gtk GUI from another process because Gtk is defined on the base process. The ImageHeight function is just a demonstration, in fact it should be much more complex.
My point is to show the progress of a long pmap process using the progress bar.

Thanks for ideas …