wpf grid as itemspaneltemplate gives inconsistent heights - wpf

Question

im trying to make a week scheduler
so for each day i have a listbox with a grid as its itemspaneltemplate , and each individual session gets its row and rowspan from the database and its working very well
the problem is when i have a short appointment so the rowspan is only 2 or 3 and the content is longer, in that case the rows containing the appointment grow to accommodate the larger content
i don't want that, id rather the appointments reflect their time span even if i don't see all data
i tried many combinations of answers that i found online
heres the whole markup
<ListBox Name="lsbTasks" Loaded="lsbTasks_Loaded_1" HorizontalContentAlignment="Stretch" ScrollViewer.HorizontalScrollBarVisibility="Disabled" VerticalContentAlignment="Stretch" >
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<Grid Initialized="Grid_Initialized_1" Background="Thistle" IsSharedSizeScope="True"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Grid.Row" Value="{Binding BusyFrom,Converter={StaticResource BusyFromConverter}}" />
<Setter Property="Grid.RowSpan" Value="{Binding BusyMinutes,Converter={StaticResource BusyMinutesConverter}}" />
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
</Style>
</ItemsControl.ItemContainerStyle>
<ListBox.ItemTemplate>
<DataTemplate>
<ScrollViewer ScrollViewer.CanContentScroll="True" ScrollViewer.VerticalScrollBarVisibility="Auto" ScrollViewer.IsDeferredScrollingEnabled="True">
<StackPanel Background="Purple" PreviewMouseDown="DockPanel_PreviewMouseDown_1">
<TextBlock TextAlignment="Center" TextWrapping="Wrap" Text="{Binding SessionPlace}" Foreground="Thistle" DockPanel.Dock="Bottom" />
<TextBlock TextAlignment="Center" TextWrapping="Wrap" Text="{Binding ClientName}" Foreground="White" FontWeight="Bold" DockPanel.Dock="Top" />
<TextBlock TextAlignment="Center" TextWrapping="Wrap" Text="{Binding OppositionName}" Foreground="White" DockPanel.Dock="Top" />
<TextBlock TextAlignment="Center" TextWrapping="Wrap" Text="{Binding SubjectName}" Foreground="Thistle" />
</StackPanel>
</ScrollViewer>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
and heres the initialization code
Private Sub Grid_Initialized_1(sender As Grid, e As EventArgs)
Dim mnts = MyWorkDaySpan.TotalMinutes
For i = 1 To mnts / 10
Dim rd = New RowDefinition With {.Height = New GridLength(1, GridUnitType.Star)}
'rd.SharedSizeGroup = "RowGroup"
sender.RowDefinitions.Add(rd)
Next
End Sub
but still the rows are uneven, as proven by the gridlines
id appreciate any help or guidance

Answer 1

You should use a different Panel, perhaps a Canvas and bind the Canvas.Top and Height properties in the ListBoxItem style.
Another alternative would be to write a custom Panel class ("CalendarPanel"), which defines two attached properties BusyFrom and BusyMinutes and arranges its child elements according to the values of these properties.