Can anyone tell by looking at this style will cause a combobox with it applied to stretch as wide as the screen unless you give it an explicit width?
<Style x:Key="ThemedComboBox" TargetType="{x:Type ComboBox}">
<Setter Property="Padding" Value="6,2,25,2"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="Foreground" Value="#FFFFFFFF"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.Resources>
<Style TargetType="ToggleButton" x:Name="comboToggleStyle">
<Setter Property="Foreground" Value="#FF333333"/>
<Setter Property="Background" Value="#FF1F3B53"/>
<Setter Property="BorderBrush">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFA3AEB9" Offset="0"/>
<GradientStop Color="#FF8399A9" Offset="0.375"/>
<GradientStop Color="#FF718597" Offset="0.375"/>
<GradientStop Color="#FF617584" Offset="1"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Padding" Value="3"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="00:00:00.1" To="MouseOver"/>
<VisualTransition GeneratedDuration="00:00:00.1" To="Pressed"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="MouseOverState" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="PressedState" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="DisabledState" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="gloss" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="0"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="PressedState" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unchecked"/>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Duration="00:00:00.0010000" Storyboard.TargetName="MouseOverState" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" Width="Auto" Height="Auto" x:Name="NormalState">
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_BackgroundGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Stroke="{StaticResource GlossyBlack_StrokeGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_HighlightGradient}"/>
</Grid>
<Grid HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" Width="Auto" Height="Auto" x:Name="MouseOverState" Opacity="0">
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_BackgroundGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Stroke="{StaticResource GlossyBlack_StrokeGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_MouseOverBackgroundGradient}"/>
</Grid>
<Grid HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" Width="Auto" Height="Auto" x:Name="PressedState" Opacity="0">
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_PressedBackgroundGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Stroke="{StaticResource GlossyBlack_StrokeGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_PressedHighlightGradient}"/>
</Grid>
<Grid HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" Width="Auto" Height="Auto" x:Name="DisabledState" Opacity="0">
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Fill="{StaticResource GlossyBlack_DisabledBackgroundGradient}"/>
<Rectangle HorizontalAlignment="Stretch" Margin="0,0,0,0" VerticalAlignment="Stretch" RadiusX="0" RadiusY="0" Stroke="{StaticResource GlossyBlack_StrokeGradient}"/>
</Grid>
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" x:Name="contentPresenter" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}"/>
<Path Height="Auto" HorizontalAlignment="Stretch" Margin="0,0,0,6" VerticalAlignment="Stretch" Stretch="Fill" Data="M100,12.903966 C59.117226,15.115555 23.108757,29.203354 -1.2437163E-14,60 L-3.2684966E-13,0 C12,-2.8610229E-06 100,0 100,0" x:Name="gloss" Fill="{StaticResource GlossyBlack_GlossGradient}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Grid.Resources>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="00:00:00.1"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="Normal"/>
<VisualState x:Name="MouseOver"/>
<VisualState x:Name="Disabled">
<Storyboard>
<DoubleAnimationUsingKeyFrames Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="(UIElement.Opacity)">
<SplineDoubleKeyFrame KeyTime="00:00:00" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard/>
</VisualState>
<VisualState x:Name="Unfocused"/>
<VisualState x:Name="FocusedDropDown">
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="00:00:00" Storyboard.TargetName="PopupBorder" Storyboard.TargetProperty="(UIElement.Visibility)">
<DiscreteObjectKeyFrame KeyTime="00:00:00">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="ContentPresenterBorder">
<Grid>
<ToggleButton BorderThickness="{TemplateBinding BorderThickness}" HorizontalContentAlignment="Right" HorizontalAlignment="Stretch" Margin="-1" x:Name="DropDownToggle" VerticalAlignment="Stretch" Foreground="{StaticResource GlossyBlack_GreyStateBackground}" BorderBrush="{StaticResource GlossyBlack_StrokeGradient}" Background="{StaticResource GlossyBlack_BackgroundGradient}" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press">
<Path Height="4" HorizontalAlignment="Right" Margin="0,0,6,0" x:Name="BtnArrow" Width="8" Stretch="Uniform" Data="F1 M 301.14,-189.041L 311.57,-189.041L 306.355,-182.942L 301.14,-189.041 Z " Fill="{StaticResource GlossyBlack_GreyStateBackground}"/>
</ToggleButton>
<ContentPresenter HorizontalAlignment="Left" Margin="3,3,23,3" x:Name="ContentSite" VerticalAlignment="Center" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" IsHitTestVisible="False"/>
</Grid>
</Border>
<Rectangle x:Name="DisabledVisualElement" IsHitTestVisible="false" Opacity="0" Fill="#A5000000" RadiusX="3" RadiusY="3"/>
<Popup IsOpen="{TemplateBinding IsDropDownOpen}" Placement="Bottom" x:Name="Popup" Focusable="False" AllowsTransparency="True" PopupAnimation="Slide">
<Grid MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}" x:Name="DropDown" SnapsToDevicePixels="True">
<Border Height="Auto" HorizontalAlignment="Stretch" x:Name="PopupBorder" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="0,0,0,0" Background="{StaticResource GlossyBlack_PopupBackgroundGradient}" BorderBrush="{StaticResource GlossyBlack_StrokeGradient}">
<ScrollViewer BorderThickness="0" Padding="1" Foreground="{StaticResource GlossyBlack_Selected}" BorderBrush="{x:Null}" SnapsToDevicePixels="True" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" CanContentScroll="True">
<ItemsPresenter/>
</ScrollViewer>
</Border>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
I tried a few things, the problem was the Path.
I removed the Stretch=”Fill” and it fixed the problem