MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        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" d:DesignWidth="400" d:DesignHeight="400"
        x:Class="S3_SimpleBackup.MainWindow"
        Title="S3_SimpleBackup"
        Width="900" Height="600"
        x:Name="frmMain">

  <Grid>

    <Grid.RowDefinitions>
      <RowDefinition Height="2"/>
      <RowDefinition Height="auto"/>
      <RowDefinition Height="*"/>
      <RowDefinition Height="2"/>
    </Grid.RowDefinitions>

    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="2"/>
      <ColumnDefinition Width="*"/>
      <ColumnDefinition Width="2"/>
    </Grid.ColumnDefinitions>

    <TabStrip x:Name="tabstrpNavigation" Grid.Row="1" Grid.Column="1">

      <TabStripItem Content="Output"/>
      <TabStripItem Content="Jobs"/>
      <TabStripItem Content="Settings"/>
      <TabStripItem Content="Help"/>
      <TabStripItem Content="Developer"/>

    </TabStrip>


    <TabControl x:Name="tbctrlMainPage"
                Grid.Row="2" Grid.Column="1"
                SelectedIndex="{Binding #tabstrpNavigation.SelectedIndex}">

      <TabItem x:Name="tabOutput">
        
        
        <Grid>

          <Grid.RowDefinitions>
            <RowDefinition Height="auto"/>
            <RowDefinition Height="*"/>
          </Grid.RowDefinitions>

          <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
          </Grid.ColumnDefinitions>

          <TextBlock Text="Simple S3-Backup" 
                     Grid.Row="0" Grid.Column="0" Margin="0,-10,0,10"
                     FontSize="22"/>
          <TextBox x:Name="edtLogOutput" TextWrapping="WrapWithOverflow"
                   AcceptsReturn="True" AcceptsTab="true" IsReadOnly="True"
                   ScrollViewer.HorizontalScrollBarVisibility="Hidden" 
                   ScrollViewer.VerticalScrollBarVisibility="Visible"
                   Grid.Row="1" Grid.Column="0"/>
          
        </Grid>
        
      </TabItem>

      <TabItem x:Name="tabJobs">
        <StackPanel Orientation="Vertical" Spacing="10">



          <TextBlock Text="Manage backup jobs:"/>

          <StackPanel x:Name="spnlJobsButtons" Orientation="Horizontal" Spacing="5">
            <Button x:Name="btnRunJob" Content="Run Selected Job" Margin="5,5,5,5" Click="btnRunjob_Clicked"/>
            <Button x:Name="btnRunAllJob" Content="Run All Jobs" Margin="5,5,5,5" Click="btnRunAllJob_Clicked" IsVisible="false"/>
            <Button x:Name="btnNewJob" Content="New Job" Margin="5,5,5,5" Click="btnNewjob_Clicked"/>
            <Button x:Name="btnEditJob" Content="Edit Job" Margin="5,5,5,5" Click="btnEditjob_Clicked"/>
            <Button x:Name="btnDeleteJob" Content="Delete Job" Margin="5,5,5,5" Click="btnDeleteJob_Clicked"/>
          </StackPanel>

          <DataGrid x:Name="dbgJobsList" CanUserReorderColumns="False"
                    IsReadOnly="True" HorizontalScrollBarVisibility="Auto"
                    Padding ="5"/>

        </StackPanel>
      </TabItem>

      <TabItem x:Name="tabSettings">
       
        <StackPanel  Orientation="Vertical" Spacing="10" Margin="10,3,10,10">
          
          <TextBlock Text="S3 Account Setup" Margin="8,8,8,8"/>
          <TextBox x:Name="edtS3Host" Watermark="S3 Host/REST Endpoint"/>
          <TextBox x:Name="edtAccessKeyID" Watermark="Access Key ID" />
          <TextBox x:Name="edtSecretAccessKey"
                    Watermark="Secret Access Key"
                    PasswordChar="*"/>
          <CheckBox x:Name="chckbxRequireLogin" Content="Encrypt API Key with password (you'll need to unlock the app on every launch)"/>
          <Button Content="Save Configuration" HorizontalAlignment="Right" Click="btnSaveS3Config_Clicked"/>

          <Grid>

            <Grid.RowDefinitions>
              <RowDefinition Height="auto"/>
              <RowDefinition Height="*"/>
            </Grid.RowDefinitions>

            <Grid.ColumnDefinitions>
              <ColumnDefinition Width="*"/>
              <ColumnDefinition Width="auto"/>
            </Grid.ColumnDefinitions>

            <TextBlock Text="Test Configuration" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" Margin="0,0,0,5"/>
            
            <TextBox x:Name="dev_edtBucketName" Grid.Row="1" Grid.Column="0"
                     Watermark="Bucket Name"/>

            <StackPanel Orientation="Horizontal" Spacing="10" Grid.Row="1" Grid.Column="1">
              <Button x:Name="dev_btnTestConnection" Content="Test Connection" Click="btnTestConnection_Clicked"/>
              <Button x:Name="dev_btnUploadTestFile" Content="Upload Test File" Click="btnUploadTestFile_Clicked"/>
            </StackPanel>

          </Grid>

          <Grid>

            <Grid.RowDefinitions>
              <RowDefinition Height="auto"/>
              <RowDefinition Height="*"/>
            </Grid.RowDefinitions>

            <Grid.ColumnDefinitions>
              <ColumnDefinition Width="*"/>
              <ColumnDefinition Width="auto"/>
            </Grid.ColumnDefinitions>

            <CheckBox x:Name="chckbxEnableEmptyBucketTool" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2"
                      Content="Enable Empty Bucket Tool"
                      Checked="chckbxEnableEmptyBucketTool_CheckChanged" Unchecked="chckbxEnableEmptyBucketTool_CheckChanged"/>

            <TextBox x:Name="edtEmptyBucketTarget" Grid.Row="1" Grid.Column="0"
                     Watermark="Bucket Name" IsEnabled="false"/>

            <Button x:Name="btnEmptyBucket" Grid.Row="1" Grid.Column="1"
                    Content="Empty Bucket" Click="btnEmptyBucket_Clicked" IsEnabled="false"/>


          </Grid>

        </StackPanel>

       
        
        
      </TabItem>

      <TabItem x:Name="tabHelp">
        <TextBlock Text="This sections is still under construction"/>
      </TabItem>

      <TabItem x:Name="tabDev">
        <Grid>

          <Grid.RowDefinitions>
            <RowDefinition Height="auto"/>
            <RowDefinition Height="*"/>
          </Grid.RowDefinitions>

          <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
          </Grid.ColumnDefinitions>

          <TextBlock Grid.Row="0"
                     Text="WARNING!&#x0a;This section is used during development.&#x0a;Do not use this section!"/>

          <StackPanel Orientation="Vertical" Spacing="10" Grid.Row="1" >

            <Button x:Name="dev_btnTestMsgBox" Content="Test Custom MessageBox" Click="dev_btnTestMsgBox_Clicked"/>
            <Button x:Name="dev_btnTestEncryption" Content="Test Encryption" Click="dev_btnTestEncrytion_Clicked"/>
            <Button x:Name="dev_btnTestSourceListing" Content="Test SourceList" Click="dev_btnTestSourceListing_Clicked"/>
            <Panel Background="WhiteSmoke" >

            </Panel>

          </StackPanel>



        </Grid>
      </TabItem>

    </TabControl>



  </Grid>

</Window>