Windows Phone 8: LongListMultiSelector not scrollable - windows-phone-8

Question

<StackPanel x:Name="LayoutRoot" Background="Transparent" >
<TextBlock Margin="20,20,0,0" Text="Type Text Here" HorizontalAlignment="Left"/>
<TextBox x:Name="SearchTextBox" IsReadOnly="False" HorizontalAlignment="Left" Margin="20,5,0,0" Height="70" Width="400" dp:TextBoxOnTextChangedDependency.UpdateSourceOnChange="True" Text="{Binding SearchBoxText, Mode=TwoWay}" >
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<cmd:EventToCommand PassEventArgsToCommand="True"
Command="{Binding ElementName=SearchTextBox, Path=DataContext.SearchTextBox_TextChangedCommand}"
/>
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBox>
<Grid x:Name="LayoutList" Background="{StaticResource PhoneChromeBrush}">
<toolkit:LongListMultiSelector x:Name="treksLocationItems" Background="Transparent"
ItemsSource="{Binding Path=TreksLocationItems}">
<toolkit:LongListMultiSelector.ItemTemplate>
<DataTemplate>
<Grid Margin="0,5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Image Width="110" Height="150" Source="{Binding PictureFilename}" VerticalAlignment="Top"/>
<StackPanel Grid.Column="1" VerticalAlignment="Top">
<TextBlock Text="{Binding Name}" Style="{StaticResource PhoneTextLargeStyle}" FontFamily="{StaticResource PhoneFontFamilySemiBold}" Margin="12,-12,12,6"/>
<TextBlock Text="{Binding ShortDescription}" Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="Wrap" FontFamily="{StaticResource PhoneFontFamilySemiBold}"/>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Address:" Style="{StaticResource PhoneTextSmallStyle}"/>
<TextBlock Text="{Binding Path=StreetName}" Style="{StaticResource PhoneTextSmallStyle}" FontFamily="{StaticResource PhoneFontFamilySemiBold}"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Site:" Style="{StaticResource PhoneTextSmallStyle}"/>
<TextBlock Text="{Binding Path=Website}" Style="{StaticResource PhoneTextSmallStyle}" FontFamily="{StaticResource PhoneFontFamilySemiBold}"/>
</StackPanel>
</StackPanel>
<i:Interaction.Triggers>
<i:EventTrigger EventName="Tap">
<cmd:EventToCommand Command="{Binding Path=DataContext.TapCommand, ElementName=searchItems}" CommandParameter="{Binding Path=Id}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</Grid>
</DataTemplate>
</toolkit:LongListMultiSelector.ItemTemplate>
</toolkit:LongListMultiSelector>
</Grid>
</StackPanel>
I have this code in XAML, a textbox for search and a multi line select list. The problem is that the multiLineList is not scrollable even if there are many items. If I remove the stackpanel and the textblock and textbox, the list works ok with scroll enabled. Any suggestion?

Answer 1

Try adding a ScrollViewer above your grid.
<ScrollViewer>
<Grid x:Name="LayoutList" ....>
...
</Grid>
</ScrollViewer>
Or you could probably replace your Grid with a ScrollViewer if you're not using it to position your elements.

Answer 2

Wraping LLMS in a ScrollViewer will destroy the item virtualization and throw an OutOfMemoryException if the collection is too long.
Expose the LLMS' inner LongListSelector, then use the ScrollTo() method to scroll to the item u want.
LongListMultiSelector llms = LongListMultiSelector as LongListMultiSelector;
if (llms != null && llms.ItemsSource.Count > 0)
{
llms.InnerLongListSelector.ScrollTo(llms.ItemsSource[llms.ItemsSource.Count - 1]);
}

Answer 3

I've encountered this weird issue and found an easy solution.
It happens for both Longlistselector and LonglistMultiselector.
When you have several controls in one page, you need to set the height of selector's row to "*" instead of "Auto" in order to make the scrolling function to work correctly.
For example :
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/> //Row def for another row
<RowDefinition Height="*"/> //Row def for your selector
</Grid.RowDefinitions>
If the RowDefinition Height not set to "*" but "Auto", scrolling for Longlistselector will not response to user's action.