ItemsControl Wrapping - xaml

Question

I have a list of dynamic data that needs to display in the following manner:
1 4 7 10
2 5 8 11
3 6 9 12
13 16 19 22
14 17 20 23
15 18 21 24
...
However my code only iterates the top portion and runs off the screen. The following code is inside a grid. What am I doing wrong?
<toolkit:WrapPanel Orientation="Vertical" Grid.Row="2" >
<ItemsControl ItemsSource="{Binding ImagingTypes, Mode=TwoWay}"
Margin="5">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<toolkit:WrapPanel Orientation="Vertical"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="5,0,5,0">
<CheckBox IsChecked="{Binding IsSelected, Mode=TwoWay}" VerticalAlignment="Top" />
<TextBlock Grid.Column="1" Text="{Binding Description}" MaxWidth="150" TextWrapping="Wrap" />
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</toolkit:WrapPanel>

Answer 1

Sorry.I don't know very well English so I couldn't understand exactly what you mean.But If you want a sequence as above and If you want to remain static position of items.You can use UniformGrid . I hope this is what you're looking for.
Here is code:
I did a listview sample;
<ListView x:Name="SharedSizeScopeListView">
<ListView.ItemsPanel>
<ItemsPanelTemplate >
<UniformGrid IsItemsHost="True" Columns="4"/>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListViewItem Content="1"/>
<ListViewItem Content="4"/>
<ListViewItem Content="7"/>
<ListViewItem Content="10"/>
<ListViewItem Content="2"/>
<ListViewItem Content="5"/>
<ListViewItem Content="8"/>
<ListViewItem Content="11"/>
<ListViewItem Content="3"/>
<ListViewItem Content="6"/>
<ListViewItem Content="9"/>
<ListViewItem Content="12"/>
<ListViewItem Content="13"/>
<ListViewItem Content="16"/>
<ListViewItem Content="19"/>
<ListViewItem Content="22"/>
<ListViewItem Content="14"/>
<ListViewItem Content="17"/>
<ListViewItem Content="20"/>
<ListViewItem Content="23"/>
<ListViewItem Content="15"/>
<ListViewItem Content="18"/>
<ListViewItem Content="21"/>
<ListViewItem Content="24"/>
</ListView>

Answer 2

I don't think that WrapPanel supports that kind of layered wrapping. The nested approach won't work -- there is no way for the inner panel to "forward" its "left-over" items to the outer panel.
The easiest approach to this depends on whether you want a fixed number of columns, or whether you want to fit to the container size. If the former, then you could use a Grid and populate its cells serially (using code-behind or a behavior), ie (0,0), (0,1), (0,2), (1,0), ..., (0,4), (0,5), (0,6), (1,4), ...
If the latter -- you want to continue laying out items horizontally until running out of room -- then a custom Panel might be required. Writing your own panels has a bit of a learning curve (you have to read up on the Silverlight layout system), but it gives you a lot of flexibility.