From cda41b26c79a92c5d77cb31b601ad1886a0e5086 Mon Sep 17 00:00:00 2001
From: punker76 <punkerat76@gmail.com>
Date: Tue, 26 May 2020 12:54:02 +0200
Subject: [PATCH] (GH-3812) Fix wrong space for Expander before expanded

---
 .../MahApps.Metro.Demo/ExampleWindows/VSDemo.xaml        | 9 ++++++++-
 src/MahApps.Metro/Controls/Helper/ExpanderHelper.cs      | 4 +++-
 src/MahApps.Metro/Styles/Controls.Expander.xaml          | 5 ++++-
 src/MahApps.Metro/Styles/VS/Expander.xaml                | 5 ++++-
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/MahApps.Metro.Samples/MahApps.Metro.Demo/ExampleWindows/VSDemo.xaml b/src/MahApps.Metro.Samples/MahApps.Metro.Demo/ExampleWindows/VSDemo.xaml
index 30c9bb7ccf..aead09e098 100644
--- a/src/MahApps.Metro.Samples/MahApps.Metro.Demo/ExampleWindows/VSDemo.xaml
+++ b/src/MahApps.Metro.Samples/MahApps.Metro.Demo/ExampleWindows/VSDemo.xaml
@@ -90,6 +90,8 @@
                 <TabItem Header="Start">
                     <Grid>
                         <Grid.RowDefinitions>
+                            <RowDefinition Height="Auto" />
+                            <RowDefinition Height="Auto" />
                             <RowDefinition Height="Auto" />
                             <RowDefinition Height="*" />
                         </Grid.RowDefinitions>
@@ -170,13 +172,18 @@
                                   Header="Hidden Stuff">
                             <StackPanel Orientation="Vertical">
                                 <TextBlock Text="...42..." />
-                                <Expander ExpandDirection="Down" Header="Second Hidden Stuff">
+                                <Expander ExpandDirection="Down"
+                                          Header="Second Hidden Stuff"
+                                          IsExpanded="True">
                                     <StackPanel Orientation="Vertical">
                                         <TextBlock Text="...is the Answer to the Ultimate Question of Life, The Universe, and Everything" />
                                     </StackPanel>
                                 </Expander>
                             </StackPanel>
                         </Expander>
+                        <Button Grid.Row="2"
+                                Margin="20"
+                                Content="Beam me up..." />
                     </Grid>
                 </TabItem>
                 <TabItem Header="Demo">
diff --git a/src/MahApps.Metro/Controls/Helper/ExpanderHelper.cs b/src/MahApps.Metro/Controls/Helper/ExpanderHelper.cs
index 922184d8b7..2010b9686b 100644
--- a/src/MahApps.Metro/Controls/Helper/ExpanderHelper.cs
+++ b/src/MahApps.Metro/Controls/Helper/ExpanderHelper.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Diagnostics;
 using System.Windows;
 using System.Windows.Controls;
@@ -121,6 +121,7 @@ private static void OnExpandStoryboardPropertyChangedCallback(DependencyObject d
                             }
 
                             expandSite.SetCurrentValue(UIElement.OpacityProperty, 1d);
+                            expandSite.SetCurrentValue(UIElement.VisibilityProperty, Visibility.Visible);
                         }
                     });
 
@@ -214,6 +215,7 @@ private static void OnCollapseStoryboardPropertyChangedCallback(DependencyObject
                             }
 
                             expandSite.SetCurrentValue(UIElement.OpacityProperty, 0d);
+                            expandSite.SetCurrentValue(UIElement.VisibilityProperty, Visibility.Collapsed);
                         }
                     });
 
diff --git a/src/MahApps.Metro/Styles/Controls.Expander.xaml b/src/MahApps.Metro/Styles/Controls.Expander.xaml
index 1616cf596b..64c4654881 100644
--- a/src/MahApps.Metro/Styles/Controls.Expander.xaml
+++ b/src/MahApps.Metro/Styles/Controls.Expander.xaml
@@ -322,6 +322,7 @@
                          To="0"
                          Duration="0:0:0.25" />
         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ExpandSite" Storyboard.TargetProperty="(UIElement.Visibility)">
+            <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}" />
             <DiscreteObjectKeyFrame KeyTime="0:0:0.25" Value="{x:Static Visibility.Collapsed}" />
         </ObjectAnimationUsingKeyFrames>
     </Storyboard>
@@ -393,8 +394,10 @@
                                     CornerRadius="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(Controls:ControlsHelper.CornerRadius), Converter={StaticResource CornerRadiusBindingConverter}, ConverterParameter={x:Static Converters:RadiusType.Top}}"
                                     DockPanel.Dock="Bottom"
                                     Focusable="false"
+                                    Opacity="0"
                                     SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
-                                    UseLayoutRounding="True">
+                                    UseLayoutRounding="True"
+                                    Visibility="Collapsed">
                                 <ContentPresenter Margin="{TemplateBinding Padding}"
                                                   Content="{TemplateBinding Content}"
                                                   ContentTemplate="{TemplateBinding ContentTemplate}"
diff --git a/src/MahApps.Metro/Styles/VS/Expander.xaml b/src/MahApps.Metro/Styles/VS/Expander.xaml
index 41eb8cbc45..a1c685c4a4 100644
--- a/src/MahApps.Metro/Styles/VS/Expander.xaml
+++ b/src/MahApps.Metro/Styles/VS/Expander.xaml
@@ -321,6 +321,7 @@
                          To="0"
                          Duration="0:0:0.1" />
         <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ExpandSite" Storyboard.TargetProperty="(UIElement.Visibility)">
+            <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}" />
             <DiscreteObjectKeyFrame KeyTime="0:0:0.1" Value="{x:Static Visibility.Collapsed}" />
         </ObjectAnimationUsingKeyFrames>
     </Storyboard>
@@ -375,8 +376,10 @@
                                     BorderThickness="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=BorderThickness, Converter={StaticResource ThicknessBindingConverter}, ConverterParameter={x:Static Converters:ThicknessSideType.Top}}"
                                     DockPanel.Dock="Bottom"
                                     Focusable="False"
+                                    Opacity="0"
                                     SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
-                                    UseLayoutRounding="True">
+                                    UseLayoutRounding="True"
+                                    Visibility="Collapsed">
                                 <ContentPresenter Margin="{TemplateBinding Padding}"
                                                   Content="{TemplateBinding Content}"
                                                   ContentTemplate="{TemplateBinding ContentTemplate}"