Some adjustments for all day items control. Removed the leaking part.

Wino.Calendar/Controls/CalendarItemControl.xaml

@@ -0,0 +1,48 @@
+<UserControl
+    x:Class="Wino.Calendar.Controls.CalendarItemControl"
+    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:helpers="using:Wino.Helpers"
+    xmlns:local="using:Wino.Calendar.Controls"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    d:DesignHeight="300"
+    d:DesignWidth="400"
+    mc:Ignorable="d">
+
+    <Grid
+        x:Name="MainGrid"
+        BorderBrush="{ThemeResource CalendarSeperatorBrush}"
+        BorderThickness="1"
+        CornerRadius="6">
+        <Grid x:Name="MainBackground" Background="{x:Bind helpers:XamlHelpers.GetSolidColorBrushFromHex(CalendarItem.AssignedCalendar.BackgroundColorHex), Mode=OneWay}" />
+        <TextBlock
+            x:Name="EventTitleTextblock"
+            Margin="2,0"
+            HorizontalAlignment="Center"
+            VerticalAlignment="Center"
+            Foreground="{x:Bind helpers:XamlHelpers.GetReadableTextColor(CalendarItem.AssignedCalendar.BackgroundColorHex), Mode=OneWay}"
+            Text="{x:Bind CalendarItem.Title}"
+            TextWrapping="Wrap" />
+
+        <VisualStateManager.VisualStateGroups>
+            <VisualStateGroup x:Name="EventDurationStates">
+                <VisualState x:Name="RegularEvent" />
+                <VisualState x:Name="AllDayEvent">
+                    <VisualState.Setters>
+                        <Setter Target="MainGrid.MinHeight" Value="25" />
+                        <Setter Target="EventTitleTextblock.Margin" Value="6,0" />
+                    </VisualState.Setters>
+                </VisualState>
+
+                <VisualState x:Name="MultiDayEvent">
+                    <VisualState.Setters>
+                        <Setter Target="MainBackground.Opacity" Value="0.6" />
+                        <Setter Target="MainGrid.CornerRadius" Value="0" />
+                        <Setter Target="MainGrid.BorderThickness" Value="0.5" />
+                    </VisualState.Setters>
+                </VisualState>
+            </VisualStateGroup>
+        </VisualStateManager.VisualStateGroups>
+    </Grid>
+</UserControl>