Presently RadCalendar does not support Persian calendar style.

Allow RadCalendar to have multiview based on years or months.

Resolution: With our latest release(Q2 2014) we are introducing new navigation mode that has very similar behavior the described one. To take the advantages of new mode you need only to set the HeaderNavigationMode property to "Zoom":
For example : this.radCalendar1.HeaderNavigationMode = HeaderNavigationMode.Zoom;

Add functionality to customize navigation steps in multiple view of the RadCalendar.

FIX. RadCalendar - add NewDate and OldDate to the SelectionEventArgs of the SelectionChanging event

It will be nice if RadCalendar can show a popup list containing years. Currently, it supports only a list of months.

RangeMinDate and RangeMaxDate properties of RadCalendar are not taken under consideration when a date is being selected.

To reproduce: 

1. When set the Disabled to true  of special day has not effect
this.radCalendar1.SpecialDays.Add(new RadCalendarDay(new DateTime(2014,7, 15)));
this.radCalendar1.SpecialDays[0].Disabled = true;

2. When set the Selected and Selectable to false, the special day is still can select and highlight
this.radCalendar1.SpecialDays[0].Selected = false;
this.radCalendar1.SpecialDays[0].Selectable = false;

Adding the following method CalendardDayCollection.AddRange(IEnumerable Of Date) is an easy way to populate the collection

HeaderWidth and HeaderHeight properties should be made RadProperties and should be declared at RadCalendarElement. This will allow our users to set these properties in theme.

Meanwhile, you can workaround this by resetting the property every time you change the number of months that RadCalendar displays. This is shown in the next code snippet:

private void radPageViewPage2_ClientSizeChanged(object sender, EventArgs e)
{
    int numViews = this.radPageViewPage2.Size.Height / 240 + 1;
    radCalendar1.MultiViewRows = numViews;
    radCalendar1.ShowFastNavigationButtons = true;
    radCalendar1.ShowFastNavigationButtons = false;
}

The following line does not move MultiMonthView to the specific date:  

radCalendar1.CalendarElement.View.ViewStartDate = new DateTime(DateTime.Now.Year, 1, 1);


Workaround: use RadCalendar's FocusedDate property instead:

radCalendar1.FocusedDate = new DateTime(2014, 1, 1);

Although RadCalendarDay has a Tooltip property, it does not show any tooltips.

Fast navigation element displays duplicated items

ADD. RadCalendar's TodayButton does not accept shortcuts.

IMPROVE. RadCalendar - expose the RefreshVisuals method of the CalendarElement

When you click on a Navigation Button with the mouse in RadCalendar and hold the button down, then it scrolls automatically to the next/previous views very fast. Same behavior should be supported by the Fast Navigation Buttons.

Setting SelectedDate via code in RadCalendar does not work when AllowMultipleSelect is false.

When a RadRichTextBox control is added as a child to RadCalendar, the Space and Enter key input is stolen by the calendar.

Workaround is available here: http://www.telerik.com/community/forums/getting-visible-dates-from-radcalendar