In this particular case, we have a custom font set to the cell element in the ElementRender event handler. When AllowFishEye functionality is enabled, it stores the default Font internally for each cell. The font cache is not reset when a custom font is applied at a later stage.

To reproduce:
public Form1()
{
    InitializeComponent();
    this.radCalendar1.RangeMinDate = new DateTime(2014, 1, 1);
    this.radCalendar1.RangeMaxDate = new DateTime(2017, 7, 17);
    this.radCalendar1.FocusedDate = new DateTime(2014, 2, 4);
    this.radCalendar1.AllowFastNavigation = true;
    this.radCalendar1.FastNavigationStep = 1; 
    this.radCalendar1.AllowMultipleView = true;
    this.radCalendar1.MultiViewColumns = 4;
    this.radCalendar1.MultiViewRows = 3;
    this.radCalendar1.CurrentViewRow = 0;  
    this.radCalendar1.CurrentViewColumn = 1;  
}

The user expects when fast navigating forward, the view to be shifted with one year = 12 months. However, each next forward fast navigation moves with 11 months. 

Workaround: 

            this.radCalendar1.CurrentViewRow = 0;  
            this.radCalendar1.CurrentViewColumn = 0;
            this.radCalendar1.CalendarElement.PreviousButton.PerformClick();

Resolution: 
Add LabelFormat property to change the format of footer. You can use the following code snippet: 
this.radCalendar1.CalendarElement.CalendarStatusElement.LabelFormat = "yy/MM/dd dddd";

To reproduce: 
1. Drag and drop RadCalendar to form
2. Set design time the AllowMultipleView property to true
3. Set design time value of the MultiViewRows and MultiViewColumns properties to 2
4. When save the form or run the project an exception is thrown. 

Workaround: 
Set the AllowMultipleView and MultiViewColumns properties with code.

FIX. RadCalendar - Incorrect week numbering

Use the following code snippet:

radCalendar1.AllowMultipleView = true;
radCalendar1.MultiViewColumns = 1;
radCalendar1.MultiViewRows = 5;
radCalendar1.ShowRowHeaders = true;

CultureInfo ci = new CultureInfo("en-US");
CalendarWeekRule weekRule = CalendarWeekRule.FirstDay;
ci.DateTimeFormat.CalendarWeekRule = weekRule;
radCalendar1.Culture = ci;

Expected behavior: when the CalendarWeekRule is FirstDay, 01/01/2013 should be displayed as week 1

Use the following code snippet:

private void radCalendar1_ViewChanged(object sender, EventArgs e)
{
    this.radCalendar1.SpecialDays.Clear();

    RadCalendarDay day = new RadCalendarDay(new DateTime(2014,04,15));
    radCalendar1.SpecialDays.Add(day);
    PictureBox pictureBox = new PictureBox();
    pictureBox.SizeMode = PictureBoxSizeMode.StretchImage;
    pictureBox.Image = Properties.Resources.home;
    RadHostItem hostItem = new RadHostItem(pictureBox);
    day.TemplateItem = hostItem;
}

Clicking the navigation buttons does not navigate you to the respective month.

Workaround: assign the RadCalendarDay.TemplateItem before adding the day in the SpecialDays collection:
private void radCalendar1_ViewChanged(object sender, EventArgs e)
{
    this.radCalendar1.SpecialDays.Clear();

    RadCalendarDay day = new RadCalendarDay(new DateTime(2014,04,15));
    PictureBox pictureBox = new PictureBox();
    pictureBox.SizeMode = PictureBoxSizeMode.StretchImage;
    pictureBox.Image = Properties.Resources.home;
    RadHostItem hostItem = new RadHostItem(pictureBox);
    day.TemplateItem = hostItem; 
    radCalendar1.SpecialDays.Add(day);
}

Note: if the initial code is used in the ViewChanging event, clicking the navigation buttons leads to freezing the application.

RadCalendar throws an exception when you change the culture to ar-SA.

When RadCalendar is docked inside a panel which is docked in a form and the calendar is in MultiMonth view, the month headers are not displayed properly.

The border of the special days in RadCalendar does not change on mouse leave.

When changing CurrentViewRow or CurrentViewColumn of RadCalendar, the header is shown even when the ShowHeader is set to false.

radCalendar €“ set AllowMultipleView to be true. Set MultiViewColumn and MultiViewRow to be 2. Try to change the Culture and you will see error:
Object reference not set to an instance of an object.

Set the RadCalendar's NavigationNextImage and NavigationPrevImage properties in design time through property grid. The assigned images is shown in the designer. When run the application the images do not be shown.

Currently the user cannot remove the FocusedDate of RadCalendar.

Add functionality to apply custom format to the current date in the footer area.

RadCalendar crashes when the focused date is set to a value out of the current view and adding rows/columns is performed.

RadCalendar should support month selection. I.e, the end-user should be able to press a single button, and all the cells from the current month should become selected.

Resolution: 

#1 This behavior could be achieved very easy with current API, so we are thinking  that there is no need to implement it in our RadCalendar as embedded functionality. 

For example: 

C#

            this.radCalendar1.AllowMultipleSelect = true;
            for (int i = 1; i <= DateTime.DaysInMonth(DateTime.Now.Year,DateTime.Now.Month); i++)
            {
                this.radCalendar1.SelectedDates.Add(new DateTime(DateTime.Now.Year, DateTime.Now.Month, i));
            }
VB

Me.radCalendar1.AllowMultipleSelect = True
For i As Integer = 1 To DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month)
Me.radCalendar1.SelectedDates.Add(New DateTime(DateTime.Now.Year, DateTime.Now.Month, i))
Next

#2 You can set ShowOtherMonthsDays to false and use ViewSelector. 

For example: 

C# 
this.radCalendar1.AllowMultipleSelect = true;
this.radCalendar1.AllowViewSelector = true;
this.radCalendar1.ShowViewSelector = true;
this.radCalendar1.ShowOtherMonthsDays = false;
VB
Me.radCalendar1.AllowMultipleSelect = True
Me.radCalendar1.AllowViewSelector = True
Me.radCalendar1.ShowViewSelector = True
Me.radCalendar1.ShowOtherMonthsDays = False