bib_Talk_Chatprogramm/bibtalk/bib-talk/MainWindow.xaml

<Window x:Class="bib_talk.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d"
        Title="MainWindow" 
        Height="700" 
        Width="1000"
        WindowStyle="None"
        AllowsTransparency="True"
        Background="Transparent"
        WindowStartupLocation="CenterScreen" ResizeMode="NoResize">
    <Window.Resources>
        <Style x:Key="InvisibleButtonStyle" TargetType="Button">
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="BorderBrush" Value="Transparent"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Setter Property="OverridesDefaultStyle" Value="True"/>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background" Value="Transparent"/>
                    <Setter Property="BorderBrush" Value="Transparent"/>
                </Trigger>
                <Trigger Property="IsPressed" Value="True">
                    <Setter Property="Background" Value="Transparent"/>
                    <Setter Property="BorderBrush" Value="Transparent"/>
                </Trigger>
            </Style.Triggers>
        </Style>
        <Style x:Key="NoHoverButtonStyle" TargetType="Button">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Button">
                        <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            Padding="{TemplateBinding Padding}">
                            <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                          VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </Window.Resources>
    <Border CornerRadius="15" BorderThickness="20" BorderBrush="#FF282828">
        <Grid Margin="-10,-10,-10,-10" Background="#FF282828">
            <Grid.RowDefinitions>
                <RowDefinition Height="289*"/>
                <RowDefinition Height="392*"/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="747*"/>
                <ColumnDefinition Width="118*"/>
                <ColumnDefinition Width="115*"/>
            </Grid.ColumnDefinitions>
            <!-- Draggable Area -->
            <Grid VerticalAlignment="Top" Height="45" Background="Transparent" MouseLeftButtonDown="DraggableArea_MouseLeftButtonDown" Margin="0,-21,0,0" Grid.ColumnSpan="3">

            </Grid>
            <Rectangle HorizontalAlignment="Left" Height="22" Margin="0,-5,0,0" Stroke="Black" Fill="Black" VerticalAlignment="Top" Width="980" Grid.ColumnSpan="3"/>
            <!-- Close Button -->
            <Button Style="{StaticResource InvisibleButtonStyle}"
                    Width="21" 
                    Height="22" 
                    VerticalAlignment="Top" 
                    HorizontalAlignment="Right" 
                    Click="CloseButton_Click" Grid.Column="2" RenderTransformOrigin="0.057,0.564" Margin="0,-5,0,0">
                <TextBlock Text="❌" 
                           FontSize="15"
                           Foreground="White" 
                           FontWeight="Bold" 
                           HorizontalAlignment="Center" 
                           VerticalAlignment="Top"/>
            </Button>
            <Grid Margin="298,17,0,176" Grid.ColumnSpan="3">
                <Rectangle Stroke="#FF6332A0" Fill="#FF6332A0" Width="682"/>
                <TextBlock Text="Name" Margin="108,18,134,18" FontSize="40"  Foreground="White" />
                <Image Source="/PICA.jpg" Width="80" Height="80" Stretch="Fill" Margin="10,8,592,7">
                    <Image.Clip>
                        <EllipseGeometry Center="40,40" RadiusX="40" RadiusY="40"/>
                    </Image.Clip>
                </Image>
            </Grid>
            <Grid Margin="76,17,454,176">
                <Rectangle Stroke="#FF282828" Fill="#FF282828"/>
                <TextBlock Text="Chats" Foreground="White" FontSize="22" Margin="10,18,134,39" />
                <TextBox
              FontSize="20"
              BorderBrush="Transparent"
              Margin="10,61,10,10"
              Background="#FF6332A0"
              Foreground="White"
              SelectionBrush="#FF6332A0" KeyDown="messageBOX_KeyDown" RenderTransformOrigin="0.5,0.5">
                    <TextBox.RenderTransform>
                        <TransformGroup>
                            <ScaleTransform ScaleY="-1"/>
                            <SkewTransform/>
                            <RotateTransform/>
                            <TranslateTransform/>
                        </TransformGroup>
                    </TextBox.RenderTransform>
                </TextBox>
            </Grid>
            <Grid Margin="0,17,676,0" Grid.RowSpan="2">
                <Rectangle Stroke="#FF323134" Fill="#FF323134"/>

            </Grid>


            <ListBox x:Name="onlineUsersListBox" Margin="76,112,454,0" d:ItemsSource="{d:SampleData ItemCount=5}" Background="#FF323134" BorderBrush="{x:Null}" SelectionChanged="onlineUsersListBox_SelectionChanged" Grid.RowSpan="2">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal" Width="205" Height="60">
                            <Ellipse Width="10" Height="10" Fill="Green" Margin="5"/>
                            <Image Source="/PICA.jpg" Width="50" Height="50" Stretch="Fill">
                                <Image.Clip>
                                    <EllipseGeometry Center="25,25" RadiusX="25" RadiusY="25"/>
                                </Image.Clip>
                            </Image>
                            <TextBlock Text="{Binding Username}" FontWeight="Bold" Foreground="#FF6332A0" RenderTransformOrigin="0.51,0.532" FontSize="18" Width="123" Height="30" Margin="10,0,0,0"/>
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
            <TextBlock HorizontalAlignment="Left" x:Name="loggedinuser" Margin="247,113,0,0" TextWrapping="Wrap" Text="xxxx" VerticalAlignment="Top" Height="84" Width="46" Foreground="White" RenderTransformOrigin="0.6,0.591"/>
            <ListBox x:Name="chatlistbox" Margin="298,112,0,50" d:ItemsSource="{d:SampleData ItemCount=5}" Background="#FF323134" BorderBrush="{x:Null}" Foreground="#FF6332A0" ScrollViewer.VerticalScrollBarVisibility="Hidden" ScrollViewer.HorizontalScrollBarVisibility="Hidden" Grid.ColumnSpan="3" Grid.RowSpan="2">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Margin="5">
                            <TextBlock  Text="{Binding Username}" FontWeight="Bold" FontSize="20"/>
                            <TextBlock Text="{Binding Timestamp, StringFormat='{}{0:yyyy-MM-dd HH:mm:ss}'}" Foreground="Gray"/>
                            <TextBlock TextWrapping="Wrap" Text="{Binding Text}" FontSize="16"/>

                        </StackPanel>

                    </DataTemplate>

                </ListBox.ItemTemplate>

            </ListBox>

            <TextBox
                         x:Name="messageBOX"
                         FontSize="20"
                         BorderBrush="Transparent"
                         Margin="298,346,76,10"
                         Background="#FF323134"
                         Foreground="White"
                         SelectionBrush="#FF6332A0" KeyDown="messageBOX_KeyDown" Grid.ColumnSpan="3" Grid.Row="1"/>
            <Button x:Name="weiterbutton" Click="send_Click" Content="Weiter" Foreground="White"  Background="#FF6332A0" BorderThickness="0" Margin="44,346,10,10" BorderBrush="{x:Null}" Style="{StaticResource NoHoverButtonStyle}" RenderTransformOrigin="0.279,0.633" Grid.Column="2" Grid.Row="1"/>




        </Grid>
    </Border>
</Window>