Inheritance: Xamarin.Forms.Label
        public TopPanelItem( string title, View contentView = null, bool isSelected = false )
        {
            HorizontalOptions = LayoutOptions.FillAndExpand;
            Padding = 8;

            titleLabel = new DefaultLabel {
                Text = title,
                HorizontalOptions = LayoutOptions.CenterAndExpand,
                FontAttributes = FontAttributes.Bold,
                CustomFontSize = NamedSize.Small
            };
            IsSelected = isSelected;
            ContentView = contentView;

            GestureRecognizers.Add(new TapGestureRecognizer {
                Command = new Command(() => OnTap.Dispatch())
            });

            Content = titleLabel;
        }
        public TaskPopup( TodoTask task, Action onCancel = null, Action onSubmit = null)
        {
            Task = task;

            SelectedDate = task.date;
            timePicker.Time = task.date.TimeOfDay;

            BackgroundColor = StyleManager.MainColor;
            WidthRequest = 300;

            titleLabel = new DefaultLabel {Text = Task.title, HorizontalOptions = LayoutOptions.CenterAndExpand};
            titleEdit = new DefaultEntry {Text = Task.title, HorizontalOptions = LayoutOptions.CenterAndExpand, BackgroundColor = Color.Transparent};
            titleEdit.WidthRequest = 250;

            var editButton = new Image {HorizontalOptions = LayoutOptions.End, Source = "edit_task.png"};
            var doneButton = new Image {HorizontalOptions = LayoutOptions.End, Source = "ok.png"};

            titlePanel = new StackLayout {
                Orientation = StackOrientation.Horizontal,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Padding = 10,
                Children = {titleLabel, editButton}
            };

            var editPanel = new StackLayout {
                Orientation = StackOrientation.Horizontal,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Padding = new Thickness(10, 0),
                Children = {titleEdit, doneButton}
            };

            topPanel = new ContentView {
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Content = titlePanel,
            };

            editButton.GestureRecognizers.Add(new TapGestureRecognizer {
                Command = new Command(() => Device.BeginInvokeOnMainThread (() => {
                    topPanel.Content = editPanel;
                    titleEdit.Focus ();
                }))
            });

            doneButton.GestureRecognizers.Add (new TapGestureRecognizer {
                Command = new Command (() => Device.BeginInvokeOnMainThread (UpdateTitle))
            });

            if (string.IsNullOrWhiteSpace (task.title)) {
                Device.BeginInvokeOnMainThread(() =>
                    {
                        topPanel.Content = editPanel;
                        titleEdit.Focus();
                        ((Entry)editPanel.Children [0]).Focus ();
                    });
                ((Entry)editPanel.Children [0]).Focus ();
            }

            popupFragment = new ContentView();
            datePicker = new PopupDatePicker {
                OnItemSelected = view => {
                    if (view != null){
                        popupFragment.Content = view;
                    }
                }
            };
            datePicker.DateChanged += (sender, e) => {
                SelectedDate = datePicker.SelectedDate;
            };
            popupFragment.Content = datePicker.DefaultView;

            var categoryIcon = new Image {HorizontalOptions = LayoutOptions.EndAndExpand, HeightRequest = 12, Source = task.GetCategory().IconSource};

            categoryPicker = new CategoryPicker();
            categoryPicker.SelectedIndex = 0;

            foreach (Category category in CategoryHelper.AllCategories) {
                categoryPicker.Items.Add (category.Name);
                if (task.category == category.Name) {
                    categoryPicker.SelectedIndex = categoryPicker.Items.Count - 1;
                }
            }

            categoryPicker.SelectedIndexChanged += ( sender, args ) => categoryIcon.Source = CategoryHelper.AllCategories[categoryPicker.SelectedIndex].IconSource;
            var selectCategoryArrow = new Image { HorizontalOptions = LayoutOptions.End, Source = "select.png", HeightRequest = 10 };
            selectCategoryArrow.GestureRecognizers.Add(new TapGestureRecognizer {
                Command = new Command(() => categoryPicker.Focus ())
            });

            var categoryLayout = new StackLayout {
                Orientation = StackOrientation.Horizontal,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Children = {
                    new DefaultLabel {Text = "Category", TextColor = StyleManager.MainColor},
                    categoryIcon,
                    categoryPicker,
                    selectCategoryArrow
                }
            };

            isFavorite = task.isFavorite;
            var starResource = isFavorite ? FAVORITE_IMG : NOT_FAVORITE_IMG;

            var favoriteLabel = new DefaultLabel { Text = "Mark as favorite", TextColor = StyleManager.MainColor };
            var favoriteImage = new Image {
                HorizontalOptions = LayoutOptions.EndAndExpand,
                Source = starResource,
                HeightRequest = 15
            };
            var favoriteLayout = new StackLayout {
                Orientation = StackOrientation.Horizontal,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Children = { favoriteLabel, favoriteImage}
            };

            favoriteImage.GestureRecognizers.Add(new TapGestureRecognizer {
                Command = new Command(() => Device.BeginInvokeOnMainThread (() => {
                    isFavorite = !isFavorite;
                    favoriteImage.Source = isFavorite ? FAVORITE_IMG : NOT_FAVORITE_IMG;
                }))
            });

            var actionText = "Create";

            if (!string.IsNullOrWhiteSpace (task.title))
                actionText = "Update";

            var buttons = new StackLayout {
                Orientation = StackOrientation.Horizontal,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                Spacing = 0,
                Children = {
                    new DefaultButton {
                        Text = "Cancel",
                        TextColor = Color.White,
                        BackgroundColor = Color.Silver,
                        HorizontalOptions = LayoutOptions.FillAndExpand,
                        Command = new Command (onCancel.Dispatch)
                    },
                    new DefaultButton {
                        Text = actionText,
                        TextColor = Color.White,
                        BackgroundColor = StyleManager.MainColor,
                        HorizontalOptions = LayoutOptions.FillAndExpand,
                        Command = new Command (() => Device.BeginInvokeOnMainThread (() => {
                            UpdateTask (task);
                            onSubmit.Dispatch ();
                        }))
                    }
                }
            };

            var mainLayout = new StackLayout {
                Padding = 15,
                BackgroundColor = StyleManager.AccentColor,
                Spacing = 20,
                Children = { // TODO time picker, pass time
                    timePicker, categoryLayout, favoriteLayout, buttons
                }
            };

            Children.Add(topPanel);
            Children.Add(datePicker);
            Children.Add(popupFragment);
            Children.Add(mainLayout);
        }