title: Blank windows with documentation examples of Gtk(0.17) (julia 1.1)
body: <p>I got an issue with Gtk.
  My code is compiling with no error, but only the windows with its title is appearing.</p>
  
  <p>So I wondered if I made something wrong and tried some examples of the documentation (see below).
  And it didn't worked either. </p>
  
  <p>I updated the packages, rm, and add again, no error. 
  No error in compiling, nothing. </p>
  
  <p>When I ask if the widgets are visible it is saying yes. </p>
  
  <p>I saw that it could be a configuration problem of gtk but with no more explanation. </p>
  
  <p>Thank you for your help !</p>
  
  <pre><code>
  using Gtk
  
  ls = GtkListStore(String, Int, Bool, Bool)
  push!(ls,("Peter",20,false,true))
  push!(ls,("Paul",30,false,true))
  push!(ls,("Mary",25,true,true))
  insert!(ls, 2, ("Susanne",35,true,true))
  
  rTxt = GtkCellRendererText()
  rTog = GtkCellRendererToggle()
  
  c1 = GtkTreeViewColumn("Name", rTxt, Dict([("text",0)]), sort_column_id=0)
  c2 = GtkTreeViewColumn("Age", rTxt, Dict([("text",1)]), sort_column_id=1)
  c3 = GtkTreeViewColumn("Female", rTog, Dict([("active",2)]), sort_column_id=2)
  
  tmFiltered = GtkTreeModelFilter(ls)
  GAccessor.visible_column(tmFiltered,3)
  tv = GtkTreeView(GtkTreeModel(tmFiltered))
  push!(tv, c1, c2, c3)
  
  selection = GAccessor.selection(tv)
  
  signal_connect(selection, "changed") do widget
    if hasselection(selection)
      currentIt = selected(selection)
  
      println("Name: ", GtkTreeModel(tmFiltered)[currentIt,1],
              " Age: ", GtkTreeModel(tmFiltered)[currentIt,1])
    end
  end
  
  ent = GtkEntry()
  
  signal_connect(ent, "changed") do widget
    searchText = get_gtk_property(ent, :text, String)
  
    for l=1:length(ls)
      showMe = true
  
      if length(searchText) &gt; 0
        showMe = showMe &amp;&amp; occursin(lowercase(searchText), lowercase(ls[l,1]))
      end
  
      ls[l,4] = showMe
    end
  end
  
  vbox = GtkBox(:v)
  push!(vbox,ent,tv)
  
  win = GtkWindow(vbox, "List View with Filter")
  showall(win)
  </code></pre>