diff --git a/Source/Libs/GLibSharp/Marshaller.cs b/Source/Libs/GLibSharp/Marshaller.cs
index 449e5b7f3..bb70434da 100644
--- a/Source/Libs/GLibSharp/Marshaller.cs
+++ b/Source/Libs/GLibSharp/Marshaller.cs
@@ -48,15 +48,14 @@ namespace GLib {
 				g_free (ptrs [i]);
 		}
 		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
-		delegate IntPtr d_g_filename_to_utf8(IntPtr mem, int len, IntPtr read, out IntPtr written, out IntPtr error);
+		delegate IntPtr d_g_filename_to_utf8(IntPtr mem, IntPtr len, IntPtr read, out IntPtr written, out IntPtr error);
 		static d_g_filename_to_utf8 g_filename_to_utf8 = FuncLoader.LoadFunction<d_g_filename_to_utf8>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GLib), "g_filename_to_utf8"));
 		
 		public static string FilenamePtrToString (IntPtr ptr) 
 		{
 			if (ptr == IntPtr.Zero) return null;
 			
-			IntPtr dummy, error;
-			IntPtr utf8 = g_filename_to_utf8 (ptr, -1, IntPtr.Zero, out dummy, out error);
+			IntPtr utf8 = g_filename_to_utf8 (ptr, (IntPtr)(-1), IntPtr.Zero, out _, out var error);
 
 			if (error != IntPtr.Zero)
 				throw new GLib.GException (error);
@@ -117,7 +116,7 @@ namespace GLib {
 			return ret;
 		}
 		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
-		delegate IntPtr d_g_filename_from_utf8(IntPtr mem, int len, IntPtr read, out IntPtr written, out IntPtr error);
+		delegate IntPtr d_g_filename_from_utf8(IntPtr mem, IntPtr len, IntPtr read, out IntPtr written, out IntPtr error);
 		static d_g_filename_from_utf8 g_filename_from_utf8 = FuncLoader.LoadFunction<d_g_filename_from_utf8>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GLib), "g_filename_from_utf8"));
 
 		public static IntPtr StringToFilenamePtr (string str) 
@@ -125,9 +124,8 @@ namespace GLib {
 			if (str == null)
 				return IntPtr.Zero;
 
-			IntPtr dummy, error;
 			IntPtr utf8 = StringToPtrGStrdup (str);
-			IntPtr result = g_filename_from_utf8 (utf8, -1, IntPtr.Zero, out dummy, out error);
+			IntPtr result = g_filename_from_utf8 (utf8, (IntPtr)(-1), IntPtr.Zero, out _, out var error);
 
 			g_free (utf8);
 			if (error != IntPtr.Zero)
diff --git a/Source/Samples/Sections/Dialogs/FileChooserDialogSection.cs b/Source/Samples/Sections/Dialogs/FileChooserDialogSection.cs
new file mode 100644
index 000000000..6c75a366a
--- /dev/null
+++ b/Source/Samples/Sections/Dialogs/FileChooserDialogSection.cs
@@ -0,0 +1,32 @@
+using Gtk;
+
+namespace Samples
+{
+    [Section(ContentType = typeof(FileChooserDialog), Category = Category.Dialogs)]
+    class FileChooserDialogSection : ListSection
+	{
+		public FileChooserDialogSection ()
+		{
+			AddItem ($"Press button to open {nameof(FileChooserDialog)} :", new FileChooserDialogDemo ("Press me"));
+		}
+	}
+
+	class FileChooserDialogDemo : Button
+	{
+		public FileChooserDialogDemo (string text) : base (text) { }
+
+		protected override void OnPressed ()
+		{
+			var fcd = new FileChooserDialog ("Open File", null, FileChooserAction.Open);
+			fcd.AddButton (Stock.Cancel, ResponseType.Cancel);
+			fcd.AddButton (Stock.Open, ResponseType.Ok);
+			fcd.DefaultResponse = ResponseType.Ok;
+			fcd.SelectMultiple = false;
+
+			ResponseType response = (ResponseType) fcd.Run ();
+			if (response == ResponseType.Ok)
+			     ApplicationOutput.WriteLine (fcd.Filename);
+			fcd.Destroy ();
+		}
+    }
+}
\ No newline at end of file