Fix FileDialog panels to allow focus on child views

Co-authored-by: tig <[email protected]>

Terminal.Gui/Views/FileDialogs/FileDialog.cs

@@ -159,7 +159,7 @@ public class FileDialog : Dialog, IDesignable
             Width = 30,
             Height = Dim.Fill (Dim.Func (_ => IsInitialized ? _btnOk.Frame.Height : 1)),
             Visible = false,
-            CanFocus = false,
+            CanFocus = true,
             TabStop = TabBehavior.NoStop,
             Arrangement = ViewArrangement.Resizable
         };
@@ -172,7 +172,7 @@ public class FileDialog : Dialog, IDesignable
             Y = Pos.Bottom (_btnBack),
             Width = Dim.Fill (),
             Height = Dim.Fill (Dim.Func (_ => IsInitialized ? _btnOk.Frame.Height : 1)),
-            CanFocus = false,
+            CanFocus = true,
             TabStop = TabBehavior.NoStop
         };