Add display for alternative definitions

- After entering the right definition for a vocabulary item, there are also alternative definitions (synonyms that could have counted as a valid answer as well) displayed on the SolutionPanel, below the entered definition.
- In order to make this fit into the current layout, the layout had to be adjusted and partially redesigned as well. It doesn't look much different, but it has been adjusted to behave as intended with different window sizes and possibilities that could occur.

src/ViewModels/LearningModes/BaseClasses/AnswerViewModelBase.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
-using Avalonia;
 using Avalonia.Media;
 using ReactiveUI;
 using VocabularyTrainer.Enums;
@@ -18,19 +18,15 @@ public abstract class AnswerViewModelBase : SingleWordViewModelBase
     private bool _isSolutionShown;
     private SolutionPanelViewModel? _solutionPanel;
     private SolidColorBrush _answerColor;
+    private bool _showPossibleSynonyms;
+    private ObservableCollection<string>? _possibleSynonyms;
 
     private int _knownWords;
     private int _wrongWords;
 
-    private readonly SolidColorBrush _blackColor 
-        = Utilities.GetResourceFromStyle<SolidColorBrush,Application>(Application.Current, "OppositeAccent", Resources.StyleIndex) 
-          ?? new(Color.Parse("#000000"));
-    private readonly SolidColorBrush _greenColor
-        = Utilities.GetResourceFromStyle<SolidColorBrush, Application>(Application.Current, "MainGreen", Resources.StyleIndex)
-          ?? new(Color.Parse("#0CA079"));
-    private readonly SolidColorBrush _redColor 
-        = Utilities.GetResourceFromStyle<SolidColorBrush, Application>(Application.Current, "MainRed", Resources.StyleIndex) 
-          ?? new(Color.Parse("#FF0000"));
+    private readonly SolidColorBrush _blackColor = Resources.OppositeAccentBrush;
+    private readonly SolidColorBrush _greenColor = Resources.MainGreenBrush;
+    private readonly SolidColorBrush _redColor = Resources.MainRedBrush;
 
     public event EventHandler? ReadyToFocus;
 
@@ -83,7 +79,21 @@ protected int WrongWords
         set => this.RaiseAndSetIfChanged(ref _wrongWords, value);
     }
 
-    protected IEnumerable<string>? PossibleDefinitions { get; set; }
+    protected List<string>? PossibleDefinitions { get; set; }
+
+    internal ObservableCollection<string>? PossibleSynonyms 
+    {
+        get => _possibleSynonyms; 
+        private set => this.RaiseAndSetIfChanged(ref _possibleSynonyms, value); 
+    }
+
+    internal string PossibleSynonymsString => PossibleSynonyms is null ? string.Empty : string.Join("; ", PossibleSynonyms);
+
+    internal bool ShowPossibleSynonyms
+    {
+        get => _showPossibleSynonyms; 
+        set => this.RaiseAndSetIfChanged(ref _showPossibleSynonyms, value);
+    }
 
     protected internal override void VisualizeLearningProgress(LearningState previousState, LearningState newState, bool hadNotAsked)
     {
@@ -116,7 +126,7 @@ protected void CheckAnswer()
         bool tolerateTransposition = CurrentLesson.Options.TolerateSwappedLetters;
 
         PossibleDefinitions ??= new List<string> {Definition};
-        string finalDefinition = string.Join(", ", this.PossibleDefinitions);
+        string finalDefinition = string.Join("; ", this.PossibleDefinitions);
         int minDistance = mistakeTolerance + 1;
         foreach (string definition in this.PossibleDefinitions)
         {
@@ -141,12 +151,22 @@ protected void CheckAnswer()
             Utilities.ChangeLearningStateThesaurus(CurrentWord, this, correct);
         else
             Utilities.ChangeLearningState(CurrentWord, this, correct, considerOverallState: true);
+
+        ShowPossibleSynonyms = PossibleDefinitions.Count > 1 && correct;
+        if (!ShowPossibleSynonyms)
+            return;
+        var possibleDefinitionsCopy = PossibleDefinitions.Clone<List<string>, string>();
+        if (possibleDefinitionsCopy is null)
+            return;
+        PossibleSynonyms = new ObservableCollection<string>(possibleDefinitionsCopy);
+        PossibleSynonyms?.Remove(finalDefinition);
+        this.RaisePropertyChanged(nameof(PossibleSynonymsString));
     }
 
     protected void ShowSolution()
     {
         PossibleDefinitions ??= new List<string> { Definition };
-        OpenSolutionPanel(this.DisplayedTerm, string.Join(", ", PossibleDefinitions), false);
+        OpenSolutionPanel(this.DisplayedTerm, string.Join("; ", PossibleDefinitions), false);
         Utilities.ChangeLearningState(CurrentWord, this, false, considerOverallState: true);
     }
 

src/ViewModels/LearningModes/ThesaurusViewModel.cs

@@ -254,13 +254,13 @@ private void SetThesaurus()
 
         if (synonymChosen && synonyms.Count > 0)
         {
-            PossibleDefinitions = synonyms.Select(x => x.Definition);
+            PossibleDefinitions = synonyms.Select(x => x.Definition).ToList();
             this.ThesaurusType = SynonymType;
             this.IndefiniteArticle = IndefiniteWithoutVowel;
         }
         else if (antonymChosen && antonyms.Count > 0)
         {
-            PossibleDefinitions = antonyms.Select(x => x.Definition);
+            PossibleDefinitions = antonyms.Select(x => x.Definition).ToList();
             this.ThesaurusType = AntonymType;
             this.IndefiniteArticle = IndefiniteWithVowel;
         }

src/Views/LearningModes/SecondaryElements/SolutionPanelView.axaml

@@ -8,10 +8,10 @@
     <Panel HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
         <Panel HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="{StaticResource OppositeAccent}"
                Opacity="0.7"/>
-        <Grid RowDefinitions="3*,1*" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="30">
-            <Grid Grid.Row="0" RowDefinitions="*,*,*" HorizontalAlignment="Stretch" VerticalAlignment="Center">
+        <Grid RowDefinitions="*,Auto" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="30">
+            <Grid Grid.Row="0" RowDefinitions="Auto,Auto,Auto" HorizontalAlignment="Stretch" VerticalAlignment="Center">
                 <Grid Grid.Row="0" ColumnDefinitions="*,Auto" HorizontalAlignment="Center" VerticalAlignment="Center"
-                      Margin="0,0,0,30">
+                      Margin="0,30">
                     <Viewbox Grid.Column="0" MaxHeight="96" HorizontalAlignment="Center" VerticalAlignment="Center">
                         <TextBlock Foreground="{StaticResource SameAccent}" FontWeight="Bold" Text="{Binding Term}"/>
                     </Viewbox>
@@ -23,11 +23,37 @@
                 <Viewbox Grid.Row="1" MaxHeight="36" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,30">
                     <TextBlock Foreground="{StaticResource SameAccent}" Text="{Binding ExplanationText}"/>
                 </Viewbox>
-                <Viewbox Grid.Row="2" MaxHeight="124" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,30,0,0">
-                    <TextBlock Foreground="{Binding AnswerViewModel.AnswerColor}" FontWeight="Bold" Text="{Binding Definition}"/>
-                </Viewbox>
+                <Grid Grid.Row="2" RowDefinitions="Auto,*" HorizontalAlignment="Stretch" VerticalAlignment="Center" 
+                      Margin="0,30">
+                    <Viewbox Grid.Row="0" MaxHeight="124" HorizontalAlignment="Center" VerticalAlignment="Center" 
+                             Margin="0,0,0,15">
+                        <TextBlock Foreground="{Binding AnswerViewModel.AnswerColor}" FontWeight="Bold" 
+                                   Text="{Binding Definition}"/>
+                    </Viewbox>
+                    <Grid Grid.Row="1" ColumnDefinitions="Auto,*" HorizontalAlignment="Center" VerticalAlignment="Center"
+                          IsVisible="{Binding AnswerViewModel.ShowPossibleSynonyms}">
+                        <TextBlock Grid.Column="0" Foreground="{StaticResource SameAccent}" FontWeight="Bold"
+                                   FontSize="28" Text="Alternative definitions:" Margin="0,0,15,0"
+                                   VerticalAlignment="Center"/>
+                        <ItemsControl Grid.Column="1" HorizontalAlignment="Stretch" VerticalAlignment="Center"
+                                      Items="{Binding AnswerViewModel.PossibleSynonyms}">
+                            <ItemsControl.ItemsPanel>
+                                <ItemsPanelTemplate>
+                                    <WrapPanel Orientation="Horizontal"/>
+                                </ItemsPanelTemplate>
+                            </ItemsControl.ItemsPanel>
+                            <ItemsControl.ItemTemplate>
+                                <DataTemplate>
+                                    <TextBlock Foreground="{Binding $parent[UserControl].DataContext.AnswerViewModel.AnswerColor}"
+                                               FontWeight="Bold" FontSize="36" TextWrapping="Wrap" Text="{Binding}"
+                                               Margin="10, 0" VerticalAlignment="Center"/>
+                                </DataTemplate>
+                            </ItemsControl.ItemTemplate>
+                        </ItemsControl>
+                    </Grid>
+                </Grid>
             </Grid>
-            <Grid Grid.Row="1" ColumnDefinitions="Auto,Auto" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,30,0,0">
+            <Grid Grid.Row="1" ColumnDefinitions="Auto,Auto" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,30,0,30">
                 <Button Grid.Column="0" Classes="highlight-no-change selectable-button-effect" Width="240" Height="70"
                         Background="{StaticResource MainGreen}" Foreground="{StaticResource SameAccent}"
                         Margin="35,0" IsVisible="{Binding !IsAnswerCorrect}" CornerRadius="10"