GTK4: How to capture names of clicked folders in the right pane of a GtkFileChooserWidget?

[fmb1 (Frédéric)]

My box runs Ubuntu 21.10 ; I use GTK4, C-language and XML description of the GUI.
I am new to GUIs in general, and to GTK4 in particular.

The program uses a GtkFileChooserWidget because I need a Widget which, in addition to being embedded to the main window, displays in its right pane the list of files & folders according to the navigation of the user.

The goal of this program is simply to capture the name of the folder (folder’s names only, not file’s names) the user just clicked on in the list of files & folders of the right pane of the GtkFileChooserWidget.

The code (see below) has 2 issues:

1. the name of the captured folder is not that of the click that has just been performed, but that of the previous click;
2. the program also capture the names of the folders after clicking on the ‘full path’ displayed in the upper part of the GtkFileChooserWidget, which this program should not authorize.

Here is the XML-code:

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <requires lib="gtk" version="4.0"/>
  <object class="GtkWindow" id="window1">
    <property name="child">
      <object class="GtkGrid" id="grid1">
        <child>
          <object class="GtkFrame" id="frame1">
            <child>
              <object class="GtkFileChooserWidget" id="folderChooserWidget1">
                <property name="action">select-folder</property>
                <property name="select-multiple">True</property>
              </object>
            </child>
          </object>
        </child>
      </object>
    </property>
  </object>
</interface>

Here is the C-code:

#include <gtk/gtk.h>
#include <glib/gprintf.h>

static void on_click (GtkGestureClick *controller, int n, double x, double y, GtkFileChooser *folderChooser)
{
  GFile *file = NULL;
  char *basename = (char *)NULL;

  file  = gtk_file_chooser_get_file (folderChooser);
  if (file == NULL)
    g_printf ("No folder selected!\n");
  else
  {
    basename = g_file_get_basename (file);
    g_printf ("folder selected: %s\n", basename);
    g_free (basename);
  }
}    

static void app_activate (GApplication *application)
{
  GtkApplication *app;
  GtkBuilder *builder1;
  GObject *window1;
  GObject *folderChooserWidget1;

  app = GTK_APPLICATION (application);

  builder1 = gtk_builder_new ();
  gtk_builder_add_from_file (builder1, "xml.ui", NULL);

  window1 = gtk_builder_get_object (builder1, "window1");
  gtk_window_set_application (GTK_WINDOW (window1), app);

  folderChooserWidget1 = gtk_builder_get_object (builder1, "folderChooserWidget1");
  GtkGesture *controller;
  controller = gtk_gesture_click_new ();
  gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (controller), 0);
  gtk_gesture_single_set_exclusive (GTK_GESTURE_SINGLE (controller), TRUE);
  gtk_event_controller_set_propagation_phase (GTK_EVENT_CONTROLLER (controller), GTK_PHASE_CAPTURE);
  g_signal_connect_after (controller, "pressed", G_CALLBACK (on_click), GTK_FILE_CHOOSER (folderChooserWidget1));
  gtk_widget_add_controller (GTK_WIDGET (folderChooserWidget1), GTK_EVENT_CONTROLLER (controller));


  gtk_widget_show (GTK_WIDGET (window1));

  g_object_unref (builder1);
}    

int main (int argc, char *argv[])
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("xx.yy.zz", G_APPLICATION_FLAGS_NONE);
  g_signal_connect (app, "activate", G_CALLBACK (app_activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);

  g_object_unref (app);

  return (status);
}

How can I solve issues 1 & 2?
Thank you for your help!