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