JPUser said:

Is there some way to do something about this so that the side-by-side appointments don't stack up on top of each other when the interval increases?

No. The activities are positioned at the pixel associated with their start time. Just as with Outlook if activities in a schedule view overlap then they are shifted to another row.

JPUser said:

Or if it's not possible, is there someway to at least prevent it from stacking on multiple levels so that those little arrows are necessary to view the rest of the levels?

The out of view indicators are their when there is not enough room to show all the activities. The height of the control does not currently consider the height of the activities since the control is designed to virtualize the timeslots and activities and because each CalendarGroup is intended to be the same size. We can try to see if this is something we can support but I cannot say for sure that we can.

JPUser said:

On a related note, how is the style of an appointment set (or more specifically, the height)?  I inherited maintenance of this screen and the person who initially set up this control is not here anymore.  I've tried to find where the style is set but haven't been successful so far..

An Appointment is represented by an AppointmentPresenter. The style and template for the AppointmentPresenter ultimately dictate the size. If you want to retemplate it then you would look in the DefaultStyles directory for the xamSchedule's xaml and create your own style/template based on the ones there. The activities are relatively complicated because they are responsible for lots of things so their template is somewhat complicated.

Ok so you have the controls within an element that is measuring its children with infinity? E.g. a horizontal stackpanel (stackpanels only measure with infinity in the direction they are arranging and width the value of the availablesize for the other constraint), a grid where the associated column definition has a width of auto, a scrollviewer where the horizontalscrollbarvisibility is auto, hidden or visible. Note, just having it within a window whose SizeToContent is Width is not enough because in that case the Window measures its children with the virtual screen width - not infinity. In that situation then the desired size should be based upon the default/preferred timeslotheader width * the number of timeslots so the control width should change.

I tried this out and currently it won't when using our GridBagPanel in the control template but if you change it to Grid and change the attached properties used in the template then it does. It is important to note though that if the width of the ancestor is less than the desired width then part of the control will be off screen. If you put it in a scrollviewer as you seem to indicate you are doing then you will be able to scroll the contents but realize that (a) there will no virtualization of elements since virtualization is based on being measured with the actual on screen available size and (b) if the scrollviewer will contain the xamschedule views then it will be scrolling the entire control and therefore the tabs on the left will scroll out of view.

Here's a modified version of the style I provided earlier but this one uses a Grid instead of a GridBagPanel.

            <Style TargetType="ig:XamScheduleView">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="ig:XamScheduleView">
                            <Border BorderBrush="{TemplateBinding BorderBrush}"
       BorderThickness="{TemplateBinding BorderThickness}"
       Background="{TemplateBinding Background}"
       Padding="{TemplateBinding Padding}"
       igPrim:XamlHelper.SnapsToDevicePixels="True">

                                <VisualStateManager.VisualStateGroups>
                                    <VisualStateGroup Name="ErrorStates">
                                        <VisualState Name="NoError"/>
                                        <VisualState Name="Error">
                                            <Storyboard Storyboard.TargetName="ErrorDisplay" Storyboard.TargetProperty="Visibility">
                                                <ObjectAnimationUsingKeyFrames>
                                                    <DiscreteObjectKeyFrame KeyTime="0">
                                                        <DiscreteObjectKeyFrame.Value>
                                                            <Visibility>Visible</Visibility>
                                                        </DiscreteObjectKeyFrame.Value>
                                                    </DiscreteObjectKeyFrame>
                                                </ObjectAnimationUsingKeyFrames>
                                            </Storyboard>
                                        </VisualState>
                                    </VisualStateGroup>
                                </VisualStateManager.VisualStateGroups>
                                <Grid x:Name="RootPanel" >
                                    <Grid igPrim:XamlHelper.SnapsToDevicePixels="{TemplateBinding igPrim:XamlHelper.SnapsToDevicePixels}">
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition Width="Auto"/>
                                            <ColumnDefinition Width="Auto"/>
                                            <ColumnDefinition Width="*"/>
                                            <ColumnDefinition Width="Auto"/>
                                        </Grid.ColumnDefinitions>
                                        <Grid.RowDefinitions>
                                            <RowDefinition Height="Auto"/>
                                            <RowDefinition Height="Auto"/>
                                            <RowDefinition Height="*"/>
                                            <RowDefinition Height="Auto"/>
                                        </Grid.RowDefinitions>
                                        <TextBlock Text="{TemplateBinding SecondaryTimeZoneLabel}" 
          VerticalAlignment="Top"
          HorizontalAlignment="Right"
          Margin="0,6,8,0"
          Grid.Row="0" 
          Grid.Column="0" 
          Visibility="{TemplateBinding SecondaryTimeZoneVisibility}" />
                                        <TextBlock Text="{TemplateBinding PrimaryTimeZoneLabel}" 
          VerticalAlignment="Top"
          HorizontalAlignment="Right"
          Margin="0,6,8,0"
          Grid.Row="1" 
          Grid.Column="0" />
                                        <igPrim:ScheduleViewTimeslotHeaderArea 
          x:Name="SecondaryTimeZone" 
          Background="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaBackgroundScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          BorderBrush="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaSeparator], RelativeSource={RelativeSource TemplatedParent}}"
          BorderThickness="0,0,0,1"
          Grid.Row="0" 
          Grid.Column="2" 
          Visibility="{TemplateBinding SecondaryTimeZoneVisibility}" />
                                        <igPrim:ScheduleViewTimeslotHeaderArea 
          x:Name="PrimaryTimeZone" 
          Background="{Binding Path=DefaultBrushProvider[TimeslotHeaderAreaBackgroundScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          Grid.Row="1" 
          Grid.Column="2" />
                                        <igPrim:ScheduleStackPanel 
          x:Name="GroupHeadersPanel" 
          Grid.Row="2" 
          Grid.Column="0" 
          Visibility="{TemplateBinding CalendarHeaderAreaVisibilityResolved}"
         />
                                        <igPrim:ScheduleStackPanel 
          x:Name="GroupsPanel" 
          Grid.Row="2" 
          Grid.Column="2" />
                                        <ScrollBar 
          Grid.Column="3" 
          Grid.Row="2" 
          Orientation="Vertical" 
           Style="{TemplateBinding ScrollBarStyle}"
          x:Name="TimeslotGroupScrollBar" />
                                        <ScrollBar 
          Grid.Column="2" 
          Grid.Row="3" 
          Orientation="Horizontal"
             Style="{TemplateBinding ScrollBarStyle}"
                                        MinHeight="0"
                                        Height="{TemplateBinding tshelper:TimeslotHelper.ScrollBarHeight}"
                                        Value="{Binding Path=(tshelper:TimeslotHelper.ScrollBarOffset), RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
          x:Name="TimeslotScrollBar" />
                                        <Rectangle
          igPrim:XamlHelper.SnapsToDevicePixels="True"
          Fill="{Binding Path=DefaultBrushProvider[TimeslotHeaderTickmarkScheduleView], RelativeSource={RelativeSource TemplatedParent}}"
          Grid.Row="0"
          Grid.Column="1"
          Grid.RowSpan="4"
                                                  Width="2"/>
                                        <!-- AS 11/11/10 NA 11.1 - CalendarHeaderAreaWidth -->
                                        <!-- Overlap the rectangle above. -->
                                        <igPrim:ScheduleResizerBar 
         x:Name="GroupHeadersResizer"
         IsEnabled="{TemplateBinding AllowCalendarHeaderAreaResizing}"
         Canvas.ZIndex="2"
         Width="4"
         Grid.Column="0" 
         Grid.ColumnSpan="2" 
         Grid.Row="0"
         Grid.RowSpan="4" 
         HorizontalAlignment="Right"
         />
                                    </Grid>
                                    <ContentControl x:Name="ErrorDisplay" 
               Visibility="Collapsed" 
               Content="{Binding Path=BlockingError, RelativeSource={RelativeSource TemplatedParent}}"
               Style="{StaticResource BlockingErrorStyle}"
               igPrim:CalendarBrushProvider.BrushProvider="{Binding Path=DefaultBrushProvider, RelativeSource={RelativeSource TemplatedParent}}"
               />
                                </Grid>
                            </Border>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>