Add GTK4 List API examples with filters and sort

[gavr123456789]

https://docs.gtk.org/gtk4/class.FileFilter.html
https://docs.gtk.org/gtk4/class.Sorter.html
https://docs.gtk.org/gtk4/class.MultiSorter.html
https://docs.gtk.org/gtk4/class.Filter.html
https://docs.gtk.org/gtk4/class.MultiFilter.html

[gavr123456789]

Sort blocked by #144
String Sorter can only work with expressions.

[gavr123456789]

File Filter C example:
https://github.com/val-verde/gtk/blob/143770f16d43245f2821d1cdddd6ec1c4d92175f/testsuite/gtk/filefilter.c
List Sorter:
https://gitlab.gnome.org/GNOME/gtk/-/blob/master/testsuite/gtk/sortlistmodel.c

[gavr123456789]

Asked for help here: https://discourse.gnome.org/t/how-to-reset-filefilter-and-how-filefilter-add-pattern-works/6996

[gavr123456789]

FullVala example with Expressions and NumericSort https://github.com/aeldemery/gtk4_list_colors/blob/master/sources/ColorGridWidget.vala#L65

[gavr123456789]

Asked for help here: https://discourse.gnome.org/t/how-to-reset-filefilter-and-how-filefilter-add-pattern-works/6996

Problem with FileFilter was solved.

[gavr123456789]

I think this is very close, but FileInfo has no propertiess, so need to use Expression with GClosure https://developer.gnome.org/gtk4/stable/GtkExpression.html#gtk-closure-expression-new

import gintro/[gtk4, gobject, gio]
import std/with

proc getFileName(info: gio.FileInfo): string =
  return info.getName()  

proc setup_cb(factory: gtk4.SignalListItemFactory, listitem: gtk4.ListItem) =
  listitem.setChild(newLabel(""))
  
proc bind_cb(factory: gtk4.SignalListItemFactory, listitem: gtk4.ListItem) =
  let 
    lb = listitem.getChild().Label
    fileobj = cast[FileInfo](listitem.getItem())
  
  lb.text = fileobj.getFileName()

proc unbind_cb(factory: gtk4.SignalListItemFactory, listitem: gtk4.ListItem) =
  # There's nothing to do here. 
  # If you does something like setting a signal in bind_cb,
  # then disconnecting the signal is necessary in unbind_cb. 
  echo "unbind"

proc teardown_cb(factory: gtk4.SignalListItemFactory, listitem: gtk4.ListItem) =
  listitem.setChild (nil)
  # When the child of listitem is set to NULL, the reference to GtkLabel will be released and lb will be destroyed. 
  # Therefore, g_object_unref () for the GtkLabel object doesn't need in the user code. 

proc entryChanged(self: EntryBuffer, position: int, chars: string, nChars: int) = 
  echo self.text


proc activate(app: gtk4.Application) =
  let
    window = newApplicationWindow(app)
    scr = newScrolledWindow()
    file = gio.newGFileForPath(".")
    dl = gtk4.newDirectoryList("standard::name", file)
    ls = listModel(dl)
    ss = newStringSorter()
    fm = newSortListModel(ls, ss)
    ns = gtk4.newNoSelection(listModel(fm))
    factory = gtk4.newSignalListItemFactory()
    lv = newListView(ns, factory)

    mainBox = newBox(Orientation.vertical, 5)
    patternEntry = newEntry()


  patternEntry.placeholderText = "Enter pattern"
  patternEntry.buffer.connect("inserted_text", entryChanged)



  with mainBox:
    append patternEntry
    append scr
  let gFileType = typeFromName("GFileInfo")
  ss.expression = newPropertyExpression(gFileType, nil, "display_name" )
  

  with scr: 
    vexpand = true
    setChild lv

  dl.setMonitored true

  with factory:
    connect("setup", setup_cb)
    connect("bind", bind_cb)
    connect("unbind", unbind_cb)
    connect("teardown", teardown_cb)

  with window:
    defaultSize = (600, 400)
    title = "Nim ListView"
    setChild mainBox
    show

proc main =
  let app = newApplication("org.gtk.example")
  app.connect("activate", activate)
  discard run(app)

main()