To reproduce:
RadScheduler radScheduler1 = new RadScheduler();
public Form1()
{
    InitializeComponent();
    radScheduler1.Top += 100;
    radScheduler1.Parent = this;
    this.radSchedulerNavigator1.AssociatedScheduler = radScheduler1;
    this.radScheduler1.ActiveViewType = SchedulerViewType.Timeline;
  

    Color[] colors = new Color[]{Color.LightBlue, Color.LightGreen, Color.LightYellow,
        Color.Red, Color.Orange, Color.Pink, Color.Purple, Color.Peru, Color.PowderBlue};
    string[] names = new string[]{"Alan Smith", "Anne Dodsworth",
         "Boyan Mastoni", "Richard Duncan", "Maria Shnaider"};
    for (int i = 0; i < names.Length; i++)
    {
        Resource resource = new Resource();
        resource.Id = new EventId(i);
        resource.Name = names[i];
        resource.Color = colors[i];
   this.radScheduler1.Resources.Add(resource);
    }

    this.radScheduler1.GroupType = GroupType.Resource;
    this.radScheduler1.ActiveView.ResourcesPerView = 2;
}

private void radButton1_Click(object sender, EventArgs e)
{
    SchedulerWeeklyCalendarPrintStyle weeklyCalendarStyle = new SchedulerWeeklyCalendarPrintStyle();
    weeklyCalendarStyle.AppointmentFont = new System.Drawing.Font("Segoe UI", 12, FontStyle.Regular);
    weeklyCalendarStyle.HeadingAreaHeight = 120;
    weeklyCalendarStyle.HoursColumnWidth = 30;

    this.radScheduler1.PrintStyle = weeklyCalendarStyle;

    this.radScheduler1.PrintPreview();
}

Workaround:
Change the view before printing.

To reproduce:

            Appointment a = new Appointment(DateTime.Now, TimeSpan.FromHours(20),"Meeting");
            a.StatusId = this.radScheduler1.Statuses.Last().Id;
            this.radScheduler1.Appointments.Add(a);

            this.radScheduler1.ShowAppointmentStatus = false;

The status for AppointmentElements is shown although it shouldn't.

Please refer to the attached sample project. When you start the application the form's text indicates how many times the AppointmentFormatting event is fired for only 30 appointments - more than 400 times. The more appointments you have , the more times the vent is initially fired,e.g. if you have 50 appointmens it is fired If you switch between the different views you will see how the counter increases its value.

Please refer to the attached gif file and sample project.

Workaround: remove the database restrictions and validate the data in the edit dialog before submitting the new appointment data.

To reproduce:

Appointment a1 = new Appointment(DateTime.Today.AddHours(10).AddMinutes(30), TimeSpan.FromMinutes(30), "A1");
Appointment a2 = new Appointment(DateTime.Today.AddHours(11) , TimeSpan.FromMinutes(30), "A2");
Appointment a3 = new Appointment(DateTime.Today.AddHours(11).AddMinutes(30), TimeSpan.FromMinutes(30), "A3");
this.radScheduler1.Appointments.Add(a1);
this.radScheduler1.Appointments.Add(a2);
this.radScheduler1.Appointments.Add(a3); 
this.radScheduler1.ActiveViewType = SchedulerViewType.Timeline;   
SchedulerTimelineView timelineView = radScheduler1.GetTimelineView();
timelineView.ShowTimescale(Timescales.Minutes);
timelineView.GetScaling().DisplayedCellsCount = 10;

Please refer to the attached sample project which incorrect behavior when scrolling is illustrated in the attached gif file.

Workaround: instead of specifying 30 minutes duration of an appointment, use 29 minutes and 59 seconds.

To reproduce:
            this.radScheduler1.ActiveViewType = Telerik.WinControls.UI.SchedulerViewType.Timeline;
            this.radScheduler1.RightToLeft = System.Windows.Forms.RightToLeft.Yes;

Please refer to the attached gif file. Select the left border of an appointment and try to resize it to the left. You will notice that you are allowed to resize it to the right and vice versa.

Workaround:           this.radScheduler1.SchedulerElement.ResizeBehavior = new MyResizingBehavior(this.radScheduler1.SchedulerElement);

public class MyResizingBehavior : AppointmentResizingBehavior
{
    RadScheduler scheduler;

    public MyResizingBehavior(SchedulerVisualElement activeOwner)
        : base(activeOwner)
    {
        scheduler = activeOwner.Scheduler;
    }

    protected override bool UpdateMouseCursor(Point mousePosition, Rectangle nearRect, Rectangle farRect)
    {
        bool result = base.UpdateMouseCursor(mousePosition, nearRect, farRect);
        if (scheduler.RightToLeft == RightToLeft.Yes )
        {
            FieldInfo leftFI = typeof(AppointmentResizingBehavior).GetField("leftResize", BindingFlags.NonPublic | BindingFlags.Instance);
            FieldInfo rightFI = typeof(AppointmentResizingBehavior).GetField("rightResize", BindingFlags.NonPublic | BindingFlags.Instance);

            if (nearRect.Contains(mousePosition) && scheduler.Cursor == Cursors.SizeWE)
            {
                leftFI.SetValue(this, false);
                rightFI.SetValue(this, true);
            }
            else if (farRect.Contains(mousePosition) && scheduler.Cursor == Cursors.SizeWE)
            {
                leftFI.SetValue(this, true);
                rightFI.SetValue(this, false);
            }
        }
        return result;
    }
}

Color[] colors = new Color[]
{
    Color.LightBlue, Color.LightGreen, Color.LightYellow,
    Color.Red, Color.Orange, Color.Pink, Color.Purple, Color.Peru, Color.PowderBlue
};
string[] names = new string[]
{
    "Alan Smith", "Anne Dodsworth",
    "Boyan Mastoni", "Richard Duncan", "Maria Shnaider"
};
for (int i = 0; i < names.Length; i++)
{
    Resource resource = new Resource();
    resource.Id = new EventId(i);
    resource.Name = names[i];
    resource.Color = colors[i];
    this.radScheduler1.Resources.Add(resource);
}
this.radScheduler1.GroupType = GroupType.Resource;
this.radScheduler1.ActiveView.ResourcesPerView = 4;
this.radScheduler1.ActiveViewType = SchedulerViewType.Timeline;
this.radScheduler1.GetTimelineView().GroupSeparatorWidth = 0;

By default, the GroupSeparatorWidth property is set to 3. If you need to remove the resources separator, it is necessary to set the GroupSeparatorWidth property to 0 which is not possible at the moment with the public API.

Workaround:

FieldInfo fi = typeof(SchedulerView).GetField("groupSeparatorWidth", BindingFlags.Instance | BindingFlags.NonPublic);
fi.SetValue(this.radScheduler1.GetTimelineView(), 0);

To reproduce: please refer to the attached sample project. Edit some appointment by changing its name or time slot. In the AppointmentChanged event the changes are stored to database. However, if you restart the application you will notice that the changes are not saved at all. 

Workaround: call the IEditableObject.EndEdit method for the affected record before saving the changes to the database.

private void RadScheduler1_AppointmentChanged(object sender, AppointmentChangedEventArgs e)
{
    IEditableObject editableObject = e.Appointment.DataItem as IEditableObject;
    if (editableObject!=null)
    {
        editableObject.EndEdit();
    }
    SaveChanges();
}

To reproduce: please run the attached sample project and have a look at the gif file.

Workaround: in the _HideWeekDays method, don't pass 0 width as a parameter in the SetColumnWidth method. Use 0.01 instead.

Run the attached project and add one appointment. Press the "save" button and restart the application.

Workaround:

private void radButton1_Click(object sender, EventArgs e)
{ 
    Telerik.WinControls.UI.Appointment a = new Telerik.WinControls.UI.Appointment(DateTime.Now, TimeSpan.FromHours(2));
    this.radScheduler1.Appointments.Add(a);
    this.radScheduler1.Appointments.Remove(a);
    dbContext.SaveChanges();
}

Workaround: create a derivative of the EditAppointmentDialog. Open the designer and adjust the form's height and button's position. Then replace the default dialog with the custom one: 

public RadForm1()
{
    InitializeComponent();
    this.radScheduler1.AppointmentEditDialogShowing += radScheduler1_AppointmentEditDialogShowing;
}
CustomEditAppointmentDialog dialog;
private void radScheduler1_AppointmentEditDialogShowing(object sender, Telerik.WinControls.UI.AppointmentEditDialogShowingEventArgs e)
{
    if (dialog==null)
    {
        dialog = new CustomEditAppointmentDialog();
    }
    e.AppointmentEditDialog = dialog;
}

How to reproduce:
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        this.radScheduler1.AppointmentAdded += radScheduler1_AppointmentAdded;

        Appointment appointment = new Appointment(DateTime.Now, TimeSpan.FromMinutes(60), "Summary", "Description");
        appointment.StatusId = 2;
        appointment.BackgroundId = 6;
        this.radScheduler1.Appointments.Add(appointment);
    }

    private void radScheduler1_AppointmentAdded(object sender, AppointmentAddedEventArgs e)
    {
        Console.WriteLine("AppointmentAdded");
    }
}

Workaround:
public Form1()
        {
            InitializeComponent();

            this.radScheduler1.Appointments.CollectionChanged += Appointments_CollectionChanged;

            Appointment appointment = new Appointment(DateTime.Now, TimeSpan.FromMinutes(60), "Summary", "Description");
            appointment.StatusId = 2;
            appointment.BackgroundId = 6;
            this.radScheduler1.Appointments.Add(appointment);
        }

        private void Appointments_CollectionChanged(object sender, Telerik.WinControls.Data.NotifyCollectionChangedEventArgs e)
        {
            if (e.Action == Telerik.WinControls.Data.NotifyCollectionChangedAction.Add)
            {
                Console.WriteLine("AppointmentAdded");    
            }
        }

To reproduce:
Image img1;
Image img2;
public RadForm1()
{
    InitializeComponent();
    new Telerik.WinControls.RadControlSpy.RadControlSpyForm().Show();
    img1 = Image.FromFile(@"..\..\delete.png");
    img2 = Image.FromFile(@"..\..\111.png");

    Color[] colors = new Color[]{Color.LightBlue, Color.LightGreen, Color.LightYellow,
.Red, Color.Orange, Color.Pink, Color.Purple, Color.Peru, Color.PowderBlue};
    string[] names = new string[]{"Alan Smith", "Anne Dodsworth",
n Mastoni", "Richard Duncan", "Maria Shnaider"};
    for (int i = 0; i < names.Length; i++)
    {
        Resource resource = new Resource();
        resource.Id = new EventId(i);
        resource.Name = names[i];
        resource.Color = colors[i];
        resource.Image = img2;
        this.radScheduler1.Resources.Add(resource);
    }

    this.radScheduler1.ActiveView.ResourcesPerView = 2;
    this.radScheduler1.GroupType = GroupType.Resource;

    SchedulerDayViewGroupedByResourceElement dayView = this.radScheduler1.SchedulerElement.ViewElement as SchedulerDayViewGroupedByResourceElement;
    
    dayView.ResourceHeaderHeight = 120;

    radScheduler1.AppointmentFormatting += RadScheduler1_AppointmentFormatting;

    radScheduler1.Appointments.Add(new Appointment(DateTime.Now.AddHours(-7), DateTime.Now.AddHours(-5), "Summary", "Description") { ResourceId = radScheduler1.Resources[0].Id });
   
}

private void RadScheduler1_AppointmentFormatting(object sender, SchedulerAppointmentEventArgs e)
{
    e.AppointmentElement.Image = img1

}

- Drag the appointment to the top if needed.
- Scroll down.

Workaround:

private void RadScheduler1_AppointmentFormatting(object sender, SchedulerAppointmentEventArgs e)
{
    if (e.AppointmentElement.Children.Count ==0)
    {
        LightVisualElement el = new LightVisualElement();
        el.DrawImage = true;
        el.Image = img1;
        e.AppointmentElement.Children.Add(el);
    }
}

To reproduce:
- Bind the scheduler using  SchedulerBindingDataSource and group by resources.
- At runtime change the data source of the SchedulerBindingDataSource.
- A System.ArgumentException is thrown. 

To reproduce:

1. Add a RadScheduler on a form and set the culture:
this.radScheduler1.Culture = new System.Globalization.CultureInfo("fa-IR");

2. In regional settings set the Format to Persian(Iran) as it is illustrated in the attached screenshot.

3. Run the application and try to add an appointment. Open the Recurrence dialog and you will get the exception.

Please refer to the attached sample project and gif file.

Workaround: this.radScheduler1.ElementProvider = new CustomSchedulerElementProvider(this.radScheduler1);

public class CustomSchedulerElementProvider : SchedulerElementProvider
{ 
    public CustomSchedulerElementProvider(RadScheduler scheduler) : base(scheduler)
    {
    }

    protected override T CreateElement<T>(SchedulerView view, object context)
    {
        if (typeof(T) == typeof(TimelineGroupingByResourcesElement))
        {
            return new CustomTimelineGroupingByResourcesElement(this.Scheduler,view)as T;
        }
         
        return base.CreateElement<T>(view, context);
    }
}

public class CustomTimelineGroupingByResourcesElement : TimelineGroupingByResourcesElement
{
    public CustomTimelineGroupingByResourcesElement(RadScheduler scheduler, SchedulerView view) : base(scheduler, view)
    {
    }

    protected override SizeF ArrangeOverride(SizeF finalSize)
    {
        RectangleF contentRect = new RectangleF(PointF.Empty, finalSize);
        int vScrollOffset = this.View.AllowResourcesScrolling ? this.ResourceScrollBarThickness : 0;

        if (this.VScrollBar != null && this.VScrollBar.Maximum < this.VScrollBar.LargeChange)
        {
            vScrollOffset = 0;
        }

        IList<SchedulerTimelineViewElement> timelineElements = this.GetChildViewElements();
        IList<LightVisualElement> viewSeparators = this.GetViewSeparators();

        List<RectangleF> resourcesBounds = new List<RectangleF>();
        List<RectangleF> separatorsBounds = new List<RectangleF>();

        int scrollBarOffset = 0;

        if (timelineElements.Count > 0)
        {
            if (timelineElements[timelineElements.Count - 1].NavigationElement.Visibility == ElementVisibility.Visible)
            {
                scrollBarOffset = 17;
            }
        }

        int headerHeight = 0;
        if (timelineElements.Count > 0 && timelineElements[0].Header.Visibility != ElementVisibility.Collapsed)
        {
            headerHeight = timelineElements[0].ViewHeaderHeight + timelineElements[0].ColumnHeaderHeight;
        }
        FieldInfo fi = typeof(TimelineGroupingByResourcesElement).GetField("leftCell", BindingFlags.Instance | BindingFlags.NonPublic);
        SchedulerCellElement leftCell = fi.GetValue(this) as SchedulerCellElement;
        FieldInfo fi2 = typeof(TimelineGroupingByResourcesElement).GetField("bottomCell", BindingFlags.Instance | BindingFlags.NonPublic);
        SchedulerCellElement bottomCell = fi2.GetValue(this) as SchedulerCellElement;
        if (leftCell != null)
        {
            RectangleF arrangeRectangle = new RectangleF(0, 0, ResourceHeaderWidth, headerHeight);
            if (this.RightToLeft)
            {
                arrangeRectangle = LayoutUtils.RTLTranslateNonRelative(arrangeRectangle, contentRect);
            }

            leftCell.Arrange(arrangeRectangle);
        }

        if (bottomCell != null)
        {
            RectangleF arrangeRectangle = new RectangleF(0, finalSize.Height - scrollBarOffset, ResourceHeaderWidth, scrollBarOffset);
            if (this.RightToLeft)
            {
                arrangeRectangle = LayoutUtils.RTLTranslateNonRelative(arrangeRectangle, contentRect);
            }

            bottomCell.Arrange(arrangeRectangle);
        }

        float separatorsWidth = this.View.GroupSeparatorWidth * (this.View.ResourcesPerView - 1);
        float resourcesHeight = finalSize.Height - separatorsWidth - headerHeight ;
        float y = 0;

        for (int i = 0; i < timelineElements.Count; i++)
        {
            SchedulerTimelineViewElement timelineElement = timelineElements[i];
            LightVisualElement separator = i < viewSeparators.Count ? viewSeparators[i] : null;

            if (timelineElement != null)
            {
                float calculatedHeight = this.GetResourceSize(i, resourcesHeight);
                RectangleF arrangeRect = new RectangleF(this.ResourceHeaderWidth, y,
                    finalSize.Width - this.ResourceHeaderWidth - vScrollOffset, calculatedHeight);

                if (i == 0)
                {
                    arrangeRect.Height += headerHeight;
                }
                else if (i == timelineElements.Count - 1)
                {
                    arrangeRect.Height = finalSize.Height - arrangeRect.Top - 1;
                }

                if (this.RightToLeft)
                {
                    arrangeRect = LayoutUtils.RTLTranslateNonRelative(arrangeRect, contentRect);
                }

                timelineElement.Arrange(arrangeRect);

                y += arrangeRect.Height;

                if (i == 0)
                {
                    arrangeRect.Height -= headerHeight;
                }
                else
                {
                    arrangeRect.Y -= headerHeight;
                }

                resourcesBounds.Add(arrangeRect);
            }

            if (separator != null)
            {
                float calculatedHeight = this.View.GroupSeparatorWidth;
                RectangleF arrangeRect = new RectangleF(this.ResourceHeaderWidth, y,
                    finalSize.Width - this.ResourceHeaderWidth - vScrollOffset, calculatedHeight);
                if (this.RightToLeft)
                {
                    arrangeRect = LayoutUtils.RTLTranslateNonRelative(arrangeRect, contentRect);
                }

                separator.Arrange(arrangeRect);
                arrangeRect.Y -= headerHeight;
                separatorsBounds.Add(arrangeRect);
                y += calculatedHeight;
            }
        }

        if (this.ResourcesHeader != null)
        {
            RectangleF arrangeRectangle = new RectangleF(0, headerHeight,
                this.ResourceHeaderWidth, finalSize.Height - scrollBarOffset - headerHeight);
            if (this.RightToLeft)
            {
                arrangeRectangle = LayoutUtils.RTLTranslateNonRelative(arrangeRectangle, contentRect);
            }
            this.ResourcesHeader.SetResourcesLayoutInfo(resourcesBounds, separatorsBounds);
            this.ResourcesHeader.Arrange(arrangeRectangle);
        }

        if (this.View.AllowResourcesScrolling)
        {
            RectangleF scrollbarRect = new RectangleF(finalSize.Width - vScrollOffset,
                0, vScrollOffset, finalSize.Height - scrollBarOffset);
            if (this.RightToLeft)
            {
                scrollbarRect = LayoutUtils.RTLTranslateNonRelative(scrollbarRect, contentRect);
            }

            this.VScrollBar.Arrange(scrollbarRect);
        }
        else
        {
            this.VScrollBar.Arrange(RectangleF.Empty);
        }

        return finalSize;
    }
}

To reproduce:

Private Sub RadForm1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim dayView As SchedulerDayView = Me.RadScheduler1.GetDayView()
    dayView.RangeFactor = ScaleRange.FiveMinutes
    Dim ruler As RulerPrimitive = TryCast(Me.RadScheduler1.SchedulerElement.ViewElement,  _
    SchedulerDayViewElement).DataAreaElement.Ruler
    ruler.FormatStrings = New RulerFormatStrings("hh", "mm", "hh", "mm")
End Sub

Add a RadScheduler to a form and use the code snippet above. Run the application and scroll to the current time to see the current time indicator. Leave the form opened so you can see it on the second monitor but focus on another application for 5 minutes. You will notice that the current time indicator won't be redrawn until you focus RadScheduler again, click on the view or perform scrolling. The expected behavior is that RadScheduler will move the current time indicator as time is ticking.

Workaround: use a timer to refresh RadScheduler at a certain interval:
        Dim timer As New Timer
        timer.Interval = 1000
        AddHandler timer.Tick, AddressOf TimerTick
        timer.Start()

Private Sub TimerTick(sender As Object, e As EventArgs)
    Me.RadScheduler1.SchedulerElement.RefreshViewElement()
End Sub

Please refer to the attached gif files. The separator ";" should be displayed when the appointment's information is displayed in a single line. Otherwise, the information should be displayed multi-line like in the OutlookSeparator.gif.

Note: you can test with different AppointmentTitleFormat.

Important: setting the Text in the AppointmentFormatting event must have higher priority than AppointmentTitleFormat!!!

Workaround:

Sub New() 
    InitializeComponent()

    Me.RadScheduler1.ElementProvider = New MyElementProvider(Me.RadScheduler1)
    Me.RadScheduler1.Appointments.Add(New Appointment(DateTime.Now, TimeSpan.FromMinutes(40), "Summary", "Description", "Location"))
End Sub

Public Class CustomAppointmentElement
Inherits AppointmentElement
    Public Sub New(scheduler As RadScheduler, view As SchedulerView, appointment As IEvent)
        MyBase.New(scheduler, view, appointment)

    End Sub

    Protected Overrides Function CreateAppointmentText() As String
        Return String.Format("{0:HH:mm} - {1:HH:mm} {3} <b>{2}</b>", Me.Appointment.Start, Me.Appointment.End, _
                             Me.Appointment.Location, Me.Appointment.Summary)
    End Function
End Class

Public Class MyElementProvider
Inherits SchedulerElementProvider
    Public Sub New(scheduler As RadScheduler)
        MyBase.New(scheduler)
    End Sub
    Protected Overrides Function CreateElement(Of T As SchedulerVisualElement)(view As SchedulerView, context As Object) As T
        If GetType(T) = GetType(AppointmentElement) Then
            Return TryCast(New CustomAppointmentElement(Me.Scheduler, view, DirectCast(context, IEvent)), T)
        End If
       
        Return MyBase.CreateElement(Of T)(view, context)
    End Function
End Class

To reproduce: please refer to the attached sample project and gif file illustrating the visual problem.

Workaround:  subscribe to the RadSchedulerNavigator.ShowWeekendStateChanged event and refresh the scheduler view element:

AddHandler Me.RadSchedulerNavigator1.ShowWeekendStateChanged, AddressOf ShowWeekendStateChanged

Private Sub ShowWeekendStateChanged(sender As Object, args As StateChangedEventArgs)
    Me.RadScheduler1.SchedulerElement.RefreshViewElement()
End Sub

The resulting behavior should be similar to having all day appointments in the control with the view having its ShowAllDayArea property set to false. Currently when printed the all day appointments are drawn in the all day area.