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wpf grid background with image brush and visual brush combined

I am trying to set an image as a background of my window. I want to apply a gradient opacity mask over the window, and have the image tiled. So far, I can get either or, but not both. Here's my lame attempt at this:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height = "40*" />
<RowDefinition Height="133*"/>
</Grid.RowDefinitions>
<Grid.Resources>
<Image x:Key="myImage" Source="/GrimshawRibbon;component/Resources/GeometricBackground.png">
<Image.OpacityMask>
<LinearGradientBrush EndPoint = "0.5,0" StartPoint="0.5,1">
<GradientStop Color = "#00000000" Offset="0.6"/>
<GradientStop Color = "#FF000000" Offset="1"/>
</LinearGradientBrush>
</Image.OpacityMask>
</Image>
<ImageBrush x:Key="imageBrush" ImageSource="/GrimshawRibbon;component/Resources/GeometricBackground.png" TileMode="Tile" ViewportUnits="Absolute" Viewport="0,0,800,800"/>
<VisualBrush x:Key="myBrush" Visual="{StaticResource myImage}" Stretch="None" TileMode="Tile"/>
</Grid.Resources>
<DockPanel LastChildFill = "False" Grid.RowSpan="2" Background="{StaticResource imageBrush}"/>
<ContentControl x:Name="MainContentControl" Content="{Binding CurrentPageViewModel}" Margin="10" Grid.Row="1"/>
<Button x:Name="btnCancel" Content="Close" Margin="0,0,90,10" HorizontalAlignment="Right" Width="75" Height="36" VerticalAlignment="Bottom" Command="{Binding CloseWindowCommand, Mode=OneWay}" CommandParameter="{Binding ElementName=win}" Grid.Row="1"/>
<Button x:Name="button" Content="?" Margin="0,0,170,10" Height="36" VerticalAlignment="Bottom" HorizontalAlignment="Right" Width="36" Command="{Binding NavigateToHelpCommand, Mode=OneWay}" Grid.Row="1"/>
<Label x:Name="label" Content="Some label" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" FontWeight="Bold" FontSize="14"/>
<TextBlock x:Name="textBlock" HorizontalAlignment="Left" Margin="10,39,0,0" TextWrapping="Wrap" Text="Some tool description that is not too long. It would be good to keep it under two sentences." VerticalAlignment="Top" Height="36" Width="272"/>
</Grid>

You may assign the DockPanel's OpacityMask:
<DockPanel Grid.RowSpan="2" Background="{StaticResource imageBrush}">
<DockPanel.OpacityMask>
<LinearGradientBrush EndPoint="0.5,0" StartPoint="0.5,1">
<GradientStop Color="#00000000" Offset="0.6"/>
<GradientStop Color="#FF000000" Offset="1"/>
</LinearGradientBrush>
</DockPanel.OpacityMask>
</DockPanel>
Or probably just use a Rectangle for the background image:
<Rectangle Grid.RowSpan="2" Fill="{StaticResource imageBrush}">
<Rectangle.OpacityMask>
<LinearGradientBrush EndPoint="0.5,0" StartPoint="0.5,1">
<GradientStop Color="#00000000" Offset="0.6"/>
<GradientStop Color="#FF000000" Offset="1"/>
</LinearGradientBrush>
</Rectangle.OpacityMask>
</Rectangle>

c# WPF application UI really slow on other computers

I don't know how vague this may sound, so if you require more information, please let me know!
I've finished my program, and I've attempted to try running it on other machines, I have not used any installers to deploy this, I just have been using the debug/release programName.exe after compiling it.
My question is that is there reason why my program is running incredibly slow when it's not running on the system it was compiled on? the entire UI lags, as in it takes several sections just to switch to another tab, while running on its native computer, it runs perfectly smooth.
I've tried the publish wizard, so I don't think that'll help. I was wondering if it has to do with any the my xaml, the DLLs, or the program's dependencies? At the moment, I don't have any sort of pictures or resources that it's relying on.
Any advice on any changes that I can make to get this running more smoothly would be greatly appreciated.
Here's my mainWindow Xaml:
<Window
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"
xmlns:custom="clr-namespace:RemotePatch"
x:Class="RemotePatch.MainWindow"
mc:Ignorable="d"
Title="Remote Patch" Height="350" Width="525" AllowsTransparency="True" WindowStyle="None" ResizeMode="CanResizeWithGrip" Loaded="Window_Loaded_1" Closed="Window_Closed">
<Window.Effect>
<DropShadowEffect BlurRadius="0" ShadowDepth="0" Direction="0" Opacity="0"/>
</Window.Effect>
<Grid RenderTransformOrigin="0.497,0.518">
<Grid.RowDefinitions>
<RowDefinition Height="32" />
<RowDefinition/>
<RowDefinition Height="317*"/>
</Grid.RowDefinitions>
<Grid.Background>
<RadialGradientBrush Center="0.5,0.6">
<GradientStop Color="#FF1A8BA2"/>
<GradientStop Color="#FF293855" Offset="1"/>
<GradientStop Color="#FF1799AE" Offset="0.043"/>
</RadialGradientBrush>
</Grid.Background>
<Rectangle Fill="#FFF4F4F5" Height="29" Stroke="Black" VerticalAlignment="Top" Opacity="0" MouseLeftButtonDown="Rectangle_MouseLeftButtonDown"/>
<TabControl x:Name="tabControl" Margin="0,5,0,16" Grid.Row="2" >
<TabControl.Resources>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Border x:Name="Border" BorderThickness="1,1,1,0" BorderBrush="Gainsboro" CornerRadius="4,4,4,4" Margin="2,0">
<ContentPresenter x:Name="ContentSite"
VerticalAlignment="Center"
HorizontalAlignment="Center"
ContentSource="Header"
Margin="10,2"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter TargetName="Border" Property="Background" Value="LightSkyBlue" />
</Trigger>
<Trigger Property="IsSelected" Value="False">
<Setter TargetName="Border" Property="Background" Value="White" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</TabControl.Resources>
<TabControl.Foreground>
<ImageBrush/>
</TabControl.Foreground>
<TabControl.BorderBrush>
<ImageBrush/>
</TabControl.BorderBrush>
<TabControl.Background>
<ImageBrush/>
</TabControl.Background>
<TabItem Header="General" Margin="0,7,0,-7">
<TabItem.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="#FF040101" Offset="1"/>
</LinearGradientBrush>
</TabItem.Background>
<Grid>
<ListBox x:Name="listBox1" Margin="4,154,358,0" Foreground="White" Background="#FF14142E"/>
<TextBox x:Name="txtFile" Height="18" Margin="79,80,264,0" TextWrapping="Wrap" VerticalAlignment="Top" Background="#FF14142E" Foreground="White" MinWidth="56"/>
<TextBox x:Name="txtPSexec" Height="18" Margin="79,47,264,0" TextWrapping="Wrap" VerticalAlignment="Top" Background="#FF14142E" Foreground="White" MinWidth="56" />
<TextBox x:Name="txtGroups" HorizontalAlignment="Left" Height="18" Margin="79,119,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="65" Background="#FF14142E" Foreground="White"/>
<Button x:Name="buttonLoad" Content="Load File" Margin="4,78,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="56" Click="Load_Clicked">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="buttonSplit" Content="Split" Margin="4,117,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="56" Click="Split_Clicked">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="buttonValidate" Content="✔" Foreground="White" Height="15" VerticalAlignment="Top" HorizontalAlignment="Right" Width="15" Click="Validate_Clicked" FontSize="10.667" RenderTransformOrigin="0.062,0" Margin="0,154,358,0" FontWeight="Bold" >
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.413"/>
<GradientStop Color="#FF6C6C6C" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="buttonPsExec" Content="PsExec" Margin="4,46,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="58" Click="Psexec_Click">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="buttonLoginMain" Content="Login" Margin="452,6,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="58" Click="Login_Clicked">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
</Grid>
</TabItem>
<TabItem Header="Log" Margin="-3,7,3,-7">
<Grid>
<Grid.Background>
<ImageBrush/>
</Grid.Background>
<RichTextBox x:Name="richTextBox1" Margin="0,6,0,5" Background="Black" Foreground="White" TextChanged="richTextBox1_TextChanged" IsReadOnly="True">
<FlowDocument>
<Paragraph>
<Run Text="Remote Patch v2.0"/>
</Paragraph>
</FlowDocument>
</RichTextBox>
</Grid>
</TabItem>
<TabItem Header="Patch" Margin="-3,7,3,-7">
<Grid Margin="0,5,0.333,-5.333">
<Grid.Background>
<ImageBrush/>
</Grid.Background>
<Button x:Name="buttonLogin" Content="Login" Margin="0,10,1,0" Foreground="White" FontWeight="Bold" Grid.Row="2" Height="20" VerticalAlignment="Top" HorizontalAlignment="Right" Width="47" Click="Login_Clicked">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<GroupBox x:Name="groupBox" Header="Predefined Patches
" Margin="27,56,87,0" VerticalAlignment="Top" Height="55" Foreground="White">
<Button x:Name="buttonPredefined" Content="Run" Margin="9,-7,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="51" Click="buttonPredefined_Click">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
</GroupBox>
<ComboBox x:Name="comboBox" Margin="132,81,102,0" VerticalAlignment="Top" Background="#FF0F0F59" SelectionChanged="comboBox_SelectionChanged" Foreground="Black" />
<GroupBox x:Name="groupBox_Copy" Header="Batch File
" Margin="27,143,82,0" VerticalAlignment="Top" Height="55" Foreground="White">
<Button x:Name="buttonBatch" Content="Run" Margin="0,40,0,-43" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="51" Click="Batch_Clicked" Visibility="Hidden">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
</GroupBox>
<TextBox x:Name="txtBatchFile" Height="23" Margin="127,168,102,0" TextWrapping="Wrap" VerticalAlignment="Top" Background="#FF14142E" Foreground="White"/>
<Button x:Name="ButtonRunBatch" Content="Run" Margin="42,168,0,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" HorizontalAlignment="Left" Width="51" Click="loopBatch_Clicked">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="buttonAddFile" Content="+" Margin="0,168,47,0" Foreground="White" FontWeight="Bold" Height="20" VerticalAlignment="Top" Click="Add_Clicked" HorizontalAlignment="Right" Width="30">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Grid HorizontalAlignment="Left" Height="35" Margin="182,198,0,0" VerticalAlignment="Top" Width="106">
<StackPanel Orientation="Horizontal" HorizontalAlignment="Left" Height="40" Margin="25,5,-13,-10" VerticalAlignment="Top" Width="94">
<TextBox x:Name="numerical" TextWrapping="Wrap" Width="34" Margin="0,10,0,9.667" Background="#FF14142E" Foreground="White" TextChanged="textBox_TextChanged"/>
<Button x:Name="button1" Content="-" HorizontalAlignment="Left" VerticalAlignment="Top" Width="14" Height="19" Margin="0,10,0,0" Background="#FFFFEFEF" FontSize="10.667" FontWeight="Bold" Click="button1_Click"/>
<Button x:Name="button" Content="+" HorizontalAlignment="Left" VerticalAlignment="Top" Width="14" Height="19" Margin="0,10,0,0" FontSize="10.667" FontWeight="Bold" Click="addNumValue"/>
</StackPanel>
</Grid>
<Label x:Name="label2" Content="Groups" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="209,231,0,0" Foreground="White"/>
</Grid>
</TabItem>
</TabControl>
<Button x:Name="button2" Content="-" Margin="0,2,53,10" Foreground="White" FontWeight="Bold" HorizontalAlignment="Right" Width="21" Click="Minimize_Click">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Button x:Name="button2_Copy" Margin="0,2,27,10" Foreground="White" HorizontalAlignment="Right" Width="21" Click="Maximize_Click">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
<Canvas>
<Rectangle Height="9" Width="9" Stroke="White" Canvas.Top="-2" Canvas.Left="-4"/>
<Rectangle Height="10" Width="10" Stroke="White" Canvas.Left="-2" Canvas.Top="-7" RenderTransformOrigin="0.5,0.5">
<Rectangle.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform/>
<RotateTransform Angle="-0.715"/>
<TranslateTransform/>
</TransformGroup>
</Rectangle.RenderTransform>
</Rectangle>
</Canvas>
</Button>
<Button x:Name="button2_Copy1" Content="X" Margin="0,2,0,10" Foreground="White" FontWeight="Bold" HorizontalAlignment="Right" Width="22" Click="button2_Copy1_Click">
<Button.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0.27"/>
<GradientStop Color="#FF4F4F4F" Offset="1"/>
</LinearGradientBrush>
</Button.Background>
</Button>
<Label x:Name="label" Content="Remote Patch" HorizontalAlignment="Left" Margin="10,0,0,0" VerticalAlignment="Top" Width="108" Foreground="White" FontSize="16" IsHitTestVisible="False"/>
<Rectangle Grid.Row="2" Height="20" VerticalAlignment="Bottom" Fill="Transparent" Margin="-1,0,0,0"/>
<Label x:Name="label1" Content="Authenticated" HorizontalAlignment="Left" Grid.Row="2" Width="84" RenderTransformOrigin="0.5,0.5" Foreground="White" Height="23" VerticalAlignment="Bottom">
<Label.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform AngleY="-0.718"/>
<RotateTransform/>
<TranslateTransform Y="-0.294"/>
</TransformGroup>
</Label.RenderTransform>
</Label>
<Ellipse x:Name="authColor" Fill="Red" HorizontalAlignment="Left" Margin="83,0,0,4" Grid.Row="2" Stroke="Black" Width="13" Height="13" VerticalAlignment="Bottom"/>
<Label x:Name="labelSettings" Content="Settings" Margin="0,-1,84,0" VerticalAlignment="Top" Foreground="#FF595555" FontWeight="Bold" HorizontalAlignment="Right" Width="56" MouseLeftButtonDown="labelSettings_MouseLeftButtonDown"/>
<Rectangle x:Name="rectangleNotification" Fill="#FFDDFF03" Grid.Row="2" Stroke="Black" Height="25" VerticalAlignment="Bottom" Opacity="0" Margin="0,0,1,0"/>
<Rectangle Height="2" Margin="30,31,30,0" Stroke="#FF444444" VerticalAlignment="Top" Grid.RowSpan="2" Opacity="0.5"/>
</Grid>
</Window>

You have a DropShadowEffect applied to your Window.
This is a problem because the DropShadowEffect uses all descendant objects to calculate the shape of the shadow. That means every single object contained in your Window is being inspected by this effect while rendering -- this takes a really long time.
Your shadow effect has 0 opacity anyway so you could just remove it.
Alternatively, you should apply the effect to a child of the Window, but make sure that child has no descendants.
The trick I use to apply the shadow to a window without destroying performance is to surround the contents of my window in a grid, place a border (or similar object) at the top of said grid (remember to assign a background to the border otherwise you won't get a shadow) and then apply the effect to the border instead of your window.
Before:
<Window x:Class="MyProject.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="300" Width="400"
WindowStyle="None" AllowsTransparency="True" Background="Transparent">
<Window.Effect>
<DropShadowEffect BlurRadius="10" ShadowDepth="0"/>
</Window.Effect>
<StackPanel Margin="8" Background="White">
<Button Margin="4">Test</Button>
<Button Margin="4">Test</Button>
<Button Margin="4">Test</Button>
</StackPanel>
</Window>
After:
<Window x:Class="MyProject.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="300" Width="400"
WindowStyle="None" AllowsTransparency="True" Background="Transparent">
<Grid Margin="8">
<Border Background="White">
<Border.Effect>
<DropShadowEffect BlurRadius="10" ShadowDepth="0"/>
</Border.Effect>
</Border>
<StackPanel>
<Button Margin="4">Test</Button>
<Button Margin="4">Test</Button>
<Button Margin="4">Test</Button>
</StackPanel>
</Grid>
</Window>
This provides the exact same appearance, but with better performance because:
The buttons are no longer involved in the calculation of the shadow
The border has no descendants, so the effect is only using the layout of the border in the calculation
General rule of thumb... Only apply the drop shadow effect to objects whose ancestors are intended to be affected by the effect.

Strange border showing up in WPF

I have an application that I am writing and its for the most part still in mockup so there is not much c# behind it.
I'm noticing a strange 1px border or separator between two sections of my window that according to the XAML should not be there, nor is it there at design time, but at run sure enough I can't get rid of it. (annotated by red arrow)
Main windows XAML:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:DS4Windows" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:Custom="http://schemas.microsoft.com/winfx/2006/xaml/presentation/ribbon" xmlns:Forms="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms" xmlns:tb="http://www.hardcodet.net/taskbar" xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" mc:Ignorable="d" x:Class="DS4Windows.MainWindow"
Title="DS4Windows DSDCS Build" Height="519" Width="965" WindowStyle="None" ResizeMode="NoResize" MinWidth="800" MinHeight="519">
<Window.Background>
<ImageBrush ImageSource="Backgrounds/BlueBG2.jpg" Stretch="UniformToFill"/>
</Window.Background>
<Window.Effect>
<DropShadowEffect/>
</Window.Effect>
<DockPanel Margin="0">
<DockPanel.Background>
<ImageBrush/>
</DockPanel.Background>
<DockPanel x:Name="TopPanel" Height="92" LastChildFill="False" VerticalAlignment="Top" DockPanel.Dock="Top" MouseDown="WindowDrag">
<DockPanel.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#7F000000" Offset="0"/>
<GradientStop Offset="1" Color="#00000000"/>
</LinearGradientBrush>
</DockPanel.Background>
<Image x:Name="ProgramIcon" Height="100" VerticalAlignment="Top" Width="100" Source="Icons/Icon.png" StretchDirection="DownOnly"/>
<Menu x:Name="MainMenu" VerticalAlignment="Top" DockPanel.Dock="Bottom" Opacity="0.9" FontSize="14">
<MenuItem x:Name="FileMenu" Header="File">
<MenuItem Header="Quit"/>
</MenuItem>
<MenuItem x:Name="ToolsMenu" Header="Tools"/>
<MenuItem x:Name="HelpMenu" Header="Help"/>
<MenuItem x:Name="AccountMenu" Header="My Account" SubmenuClosed="AccountMenu_SubmenuClosed">
<MenuItem x:Name="UsernameMenuItem" Template="{DynamicResource NoHoverMenu}">
<MenuItem.Header>
<StackPanel Orientation="Horizontal">
<Label Content="Username" Width="76" Padding="0"/>
<TextBox x:Name="UsernameInput" Width="134"/>
</StackPanel>
</MenuItem.Header>
</MenuItem>
<MenuItem x:Name="PasswordMenuItem" Template="{DynamicResource NoHoverMenu}">
<MenuItem.Header>
<StackPanel Orientation="Horizontal">
<Label Content="Password" Width="76" Padding="0"/>
<PasswordBox x:Name="PasswordInput" Width="134"/>
</StackPanel>
</MenuItem.Header>
</MenuItem>
<MenuItem x:Name="LoginMenuStatus" Header="" Template="{DynamicResource NoHoverMenu}" Foreground="#FF515151" FontSize="11" Visibility="Collapsed"/>
<MenuItem x:Name="LoginButtonMenuItem" Template="{DynamicResource NoHoverMenu}">
<MenuItem.Header>
<Button x:Name="LoginButton" Content="Login" Click="LoginButton_Click"/>
</MenuItem.Header>
</MenuItem>
<Separator x:Name="LoginMenuSeperator"/>
<MenuItem x:Name="RegisterAccountMenuItem" Header="Register account"/>
<MenuItem x:Name="ForgotLoginMenuItem" Header="Forgot login"/>
<MenuItem x:Name="LogoutMenuItem" Header="Logout" Visibility="Collapsed" Click="LogoutMenuItem_Click"/>
</MenuItem>
</Menu>
<Label x:Name="WindowTitle" Content="DS4Windows DSDCS Build (1.5 ALPHA)" Height="30" Margin="5,5,100,0" VerticalAlignment="Top" DockPanel.Dock="Top" FontSize="14" Foreground="White" HorizontalAlignment="Center"/>
<StackPanel x:Name="ExitMenu" Width="100" DockPanel.Dock="Right" Margin="0,-35,0,0" RenderTransformOrigin="0.525,0.211" HorizontalAlignment="Right" MouseLeave="StackPanel_MouseLeave" Panel.ZIndex="2">
<Button x:Name="CloseButton" Content="X" Height="22" VerticalAlignment="Top" Margin="0,5,5,0" Background="#FFFF7878" FontWeight="Bold" Click="CloseButton_Click" RenderTransformOrigin="0.45,0.421" HorizontalAlignment="Right" Width="22" MouseEnter="CloseButton_MouseEnter"/>
<Button x:Name="MinimizeCloseOpt" Content="Minimize to tray" Visibility="Hidden" Click="MinimizeCloseOpt_Click"/>
<Button x:Name="QuitCloseOpt" Content="Quit" Visibility="Hidden" Click="QuitCloseOpt_Click"/>
</StackPanel>
<Label x:Name="UsernameLabel" Content="Guest" Height="28" VerticalAlignment="Bottom" DockPanel.Dock="Right" Margin="0,0,-100,0" HorizontalAlignment="Right" Foreground="White"/>
</DockPanel>
<DockPanel x:Name="Footer" Height="28" LastChildFill="False" VerticalAlignment="Top" DockPanel.Dock="Bottom">
<Image VerticalAlignment="Bottom" DockPanel.Dock="Right" Source="Icons/ResizeGrip.png" Stretch="None" HorizontalAlignment="Right" PreviewMouseLeftButtonDown="WindowResize" Cursor="SizeNWSE">
<Image.OpacityMask>
<ImageBrush ImageSource="Icons/ResizeGrip.png" Stretch="None"/>
</Image.OpacityMask>
</Image>
</DockPanel>
<DockPanel x:Name="AddPanel" Height="94" LastChildFill="False" VerticalAlignment="Top" DockPanel.Dock="Bottom" HorizontalAlignment="Center">
<Frame Content="Frame" Height="90" VerticalAlignment="Top" Width="728" Source="http://dsdcs.com/index.php?template=frontend" HorizontalAlignment="Center" RenderTransformOrigin="0.5,0.5"/>
</DockPanel>
<DockPanel x:Name="SidebarDockPanel" Background="#CCFFFFFF" Margin="0">
<StackPanel Height="305" VerticalAlignment="Top" Margin="0">
<telerik:RadOutlookBarItem Header="Home" Icon="Icons/Home.ico" IsSelected="True" FontSize="14">
<Grid Background="Transparent"/>
</telerik:RadOutlookBarItem>
<telerik:RadOutlookBarItem Header="Macros" Icon="Icons/Macros.ico" Height="38" FontSize="14">
<Grid Background="Transparent"/>
</telerik:RadOutlookBarItem>
<telerik:RadOutlookBarItem Header="Log" Icon="Icons/Log.ico" Height="38" FontSize="14">
<Grid Background="Transparent"/>
</telerik:RadOutlookBarItem>
<telerik:RadOutlookBarItem Header="Settings" Icon="Icons/Settings.ico" Height="38" FontSize="14">
<Grid Background="Transparent"/>
</telerik:RadOutlookBarItem>
</StackPanel>
</DockPanel>
<DockPanel x:Name="MainWinDockPanel" Background="#CCFFFFFF">
<Expander x:Name="CurrentGameWindow" Header="Currently Playing: Nothing" VerticalAlignment="Bottom" DockPanel.Dock="Bottom" Background="#B2000000" Foreground="White" FontWeight="Bold" FontSize="14" Panel.ZIndex="1" BorderBrush="{x:Null}" BorderThickness="0">
<DockPanel Height="128" VerticalAlignment="Top" DockPanel.Dock="Bottom" UseLayoutRounding="False">
<Image x:Name="CurrentGameBoxart" Height="128" VerticalAlignment="Top" RenderOptions.BitmapScalingMode="HighQuality">
<Image.OpacityMask>
<ImageBrush ImageSource="TempImages/5647-1.jpg"/>
</Image.OpacityMask>
</Image>
<Grid x:Name="CurrentGameBGFrame" Margin="0">
<Image x:Name="CurrentGameRating" HorizontalAlignment="Left" Height="16" Margin="12,55,0,0" VerticalAlignment="Top" Width="80"/>
<Label x:Name="CurrentGamePublisher" Content="" HorizontalAlignment="Left" Margin="12,3,0,0" VerticalAlignment="Top" Foreground="White" FontSize="12"/>
<Label x:Name="CurrentGameDeveloper" Content="" HorizontalAlignment="Left" Margin="12,24,0,0" VerticalAlignment="Top" Foreground="White" FontSize="12"/>
<Label x:Name="CurrentGameGenres" Content="" HorizontalAlignment="Left" Margin="329,3,0,0" VerticalAlignment="Top" Foreground="White" FontSize="12"/>
<Label x:Name="CurrentGamePlayers" Content="" HorizontalAlignment="Left" Margin="329,24,0,0" VerticalAlignment="Top" Foreground="White" FontSize="12"/>
</Grid>
</DockPanel>
</Expander>
<ScrollViewer Grid.Row="1" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" >
<Frame x:Name="MainNav" Content="Frame" Source="/DS4Windows;component/Pages/Home.xaml" BorderThickness="0" Margin="0"/>
</ScrollViewer>
</DockPanel>
</DockPanel>
</Window>
Child page XAML:
<Page x:Class="DS4Windows.Pages.Home"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
Title="Home" Margin="0" HorizontalAlignment="Left" VerticalAlignment="Top">
<StackPanel x:Name="ControllerStack" Margin="0">
<StackPanel Height="69" Orientation="Horizontal">
<Image x:Name="Icon1" Width="61" Source="/DS4Windows;component/ControllerStates/wireless-icon-48.png"/>
<StackPanel Margin="30,0,0,0">
<ProgressBar x:Name="BatteryMeter1" Height="20" Margin="0,18,0,0" Width="150">
<ProgressBar.Foreground>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFFF4C4C" Offset="0"/>
<GradientStop Color="#FF830000" Offset="1"/>
</LinearGradientBrush>
</ProgressBar.Foreground>
</ProgressBar>
<Label x:Name="ChargeStatus1" Content="" HorizontalAlignment="Center"/>
</StackPanel>
</StackPanel>
<StackPanel Height="69" Orientation="Horizontal">
<Image x:Name="Icon2" Width="61" Source="/DS4Windows;component/ControllerStates/DS4_C_Gray-icon-48.png"/>
<StackPanel Margin="30,0,0,0">
<ProgressBar x:Name="BatteryMeter2" Height="20" Margin="0,18,0,0" Width="150">
<ProgressBar.Foreground>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF37E03F" Offset="0"/>
<GradientStop Color="#FF1F9524" Offset="1"/>
</LinearGradientBrush>
</ProgressBar.Foreground>
</ProgressBar>
<Label x:Name="ChargeStatus2" Content="" HorizontalAlignment="Center"/>
</StackPanel>
</StackPanel>
<StackPanel Height="69" Orientation="Horizontal">
<Image x:Name="Icon3" Width="61" Source="/DS4Windows;component/ControllerStates/DS4_C_Gray-icon-48.png"/>
<StackPanel Margin="30,0,0,0">
<ProgressBar x:Name="BatteryMeter3" Height="20" Margin="0,18,0,0" Width="150">
<ProgressBar.Foreground>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF37E03F" Offset="0"/>
<GradientStop Color="#FF1F9524" Offset="1"/>
</LinearGradientBrush>
</ProgressBar.Foreground>
</ProgressBar>
<Label x:Name="ChargeStatus3" Content="" HorizontalAlignment="Center"/>
</StackPanel>
</StackPanel>
<StackPanel Height="69" Orientation="Horizontal">
<Image x:Name="Icon4" Width="61" Source="/DS4Windows;component/ControllerStates/DS4_C_Gray-icon-48.png"/>
<StackPanel Margin="30,0,0,0">
<ProgressBar x:Name="BatteryMeter4" Height="20" Margin="0,18,0,0" Width="150">
<ProgressBar.Foreground>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF37E03F" Offset="0"/>
<GradientStop Color="#FF1F9524" Offset="1"/>
</LinearGradientBrush>
</ProgressBar.Foreground>
</ProgressBar>
<Label x:Name="ChargeStatus4" Content="" HorizontalAlignment="Center"/>
</StackPanel>
</StackPanel>
</StackPanel>
</Page>

If you want to understand why things in WPF looking odd or how they render you should take a look at Snoop.
Hint: If you want to jump to the current Control move the mouse over it and press Shift + Ctrl

So, not an 100% answer to the question of why, but a fix; I added both the sidebar and main window dock panels to a new parent dockpanel control ans set the opaque background on that wrather the child controls. This got rid of the border which I suspect was actually a gap.
The why, at least I think; With all child and parent controls on the sidebar set to auto the width was being determined by calculating the width of the button string + image + padding. Since WPF is hardware rendered the width could have calculated it with aliasing considered and the response may have been a floating point number rather than an integer like if I manually set the width myself. so with a floating point width the aliasing of the two adjacent controls likely caused a fraction of a pixel width of background to show through, result in a 1px line or border as I thought it was. And since design time renders the control in SW mode this was never seen until the application was actually run.
Not sure if its taboo to answer my own ? but I figured I would for others sake who may come here with same issue.

The answers in this question may be helpfull
How to fix empty space between a border and a background in button with rounded corners?
WPF renders the elements with anti-aliasing by default and this can
result in small gaps between shapes.
Set the EdgeMode to Aliased on your Border this should get rid
of the small gap
RenderOptions.EdgeMode="Aliased"

Expanding buttons

I've created a window with a bunch of buttons. Those buttons are a usercontrol I created.
This is what my window looks like now, it contains 11 of my usercontrols, but the number of usercontrols on the window are dynamically:
When the users hovers over a button with his mouse, I want the control to expand 20 pixels.
The problem is that the control expands, but the other controls stay at their place so they overlapse.
This is my UserControl
<UserControl
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"
x:Class="UserControlSolution.UserControlButton"
x:Name="UserControl"
Height="50">
<UserControl.Resources>
<Storyboard x:Key="OnMouseEnter1">
<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)" Storyboard.TargetName="rectangle">
<EasingDoubleKeyFrame KeyTime="0" Value="1.5"/>
</DoubleAnimationUsingKeyFrames>
<DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)" Storyboard.TargetName="rectangle">
<EasingDoubleKeyFrame KeyTime="0" Value="12.5"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</UserControl.Resources>
<UserControl.Triggers>
<EventTrigger RoutedEvent="Mouse.MouseEnter">
<BeginStoryboard Storyboard="{StaticResource OnMouseEnter1}"/>
</EventTrigger>
</UserControl.Triggers>
<Grid x:Name="LayoutRoot" Height="50">
<Rectangle x:Name="rectangle" RenderTransformOrigin="0.5,0.5">
<Rectangle.Stroke>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF5C5C5C" Offset="0"/>
<GradientStop Color="#FF4E4E4E" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Stroke>
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF626262" Offset="0"/>
<GradientStop Color="#FF3B3B3B" Offset="0.987"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<TextBlock x:Name="NameLabel" FontFamily="Levenim MT" FontSize="16" Foreground="#FFE5E5E5" Height="34" Width="230" Text="Onthaal Telefoon" VerticalAlignment="Top" TextAlignment="Center" HorizontalAlignment="Center" Margin="0,10,0,0"/>
</Grid>
This is my window
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:UserControlSolution" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="UserControlSolution.MainWindow"
Title="MainWindow" Height="836" Width="262" Background="#FF2B2B2B" BorderBrush="{DynamicResource Border}" Loaded="Window_Loaded" >
<Window.Resources>
<LinearGradientBrush x:Key="Border" EndPoint="0.5,1" MappingMode="RelativeToBoundingBox" StartPoint="0.5,0">
<GradientStop Color="#FF6C6C6C" Offset="0.009"/>
<GradientStop Color="#FFA1A1A1" Offset="1"/>
</LinearGradientBrush>
</Window.Resources>
<StackPanel Margin="0,10,0,0">
<local:UserControlButton x:Name="Robby" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Erwin" HorizontalAlignment="Center" Height="50" VerticalAlignment="Top" Width="228" Background="Black" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Laurens" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Kevin" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Liesbeth" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Jack" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Filip" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Stefaan" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Sami" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Jurgen" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
<local:UserControlButton x:Name="Thomas" HorizontalAlignment="Center" Width="228" Background="Black" Height="50" VerticalAlignment="Top" Margin="0,0,0,10"/>
</StackPanel>
How can I move the controls under the expanding control down so that they don't overlapse?
Or what is a better solution?

You have to change the LayoutTransform and not the RenderTransform in order to affect the layouting of the other elements

Silverlight change button text

I have a button with multiple contetnt. I want to change it's text when the button is clicked.
XAML:
<Button HorizontalAlignment="Left" Height="114" Margin="33,58,0,0" VerticalAlignment="Top" Width="224" Style="{StaticResource GlassButtonStyle}" FontSize="26.667" Click="Button_Click_1" Name="button1">
<StackPanel Orientation="Horizontal">
<Rectangle Height="69" Stroke="Black" Width="69">
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.004,1.044" StartPoint="0.739,0.25">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="White" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<ContentPresenter Content="Clicke me" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</StackPanel>
</Button>
C# code:
button1.Content = "Hello world";
This makes the rectangle disappear, though I want only to change the text. How can I do this?

You need to modify the Control Template of Button to show your rectangle all the time.
<Button HorizontalAlignment="Left" Height="114" Margin="33,58,0,0" VerticalAlignment="Top" Width="224" Style="{StaticResource GlassButtonStyle}" FontSize="26.667" Click="Button_Click_1" Name="button1" Content="Click Me">
<Button.Template>
<ControlTemplate>
<StackPanel Orientation="Horizontal">
<Rectangle Height="69" Stroke="Black" Width="69">
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.004,1.044" StartPoint="0.739,0.25">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="White" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<ContentPresenter Content="{TemplateBinding Content}" />
</StackPanel>
</ControlTemplate>
</Button.Template>
</Button>
See Using Control Templates to Customize a Control's Look and Feel