To reproduce the issue:
1. Add a RadDateTimePicker control to a Windows Forms application.
2. Use the "ar-SA" culture.
3. Attempt to manually enter a date in the RadDateTimePicker control using letters or special characters.
Dim hijriCulture As New CultureInfo("ar-SA")
hijriCulture.DateTimeFormat.Calendar = New HijriCalendar()
RadDateTimePicker1.Format = DateTimePickerFormat.Custom
RadDateTimePicker1.Culture = hijriCulture
The selected date is 2024 Feb 29. A custom date format is applied to the control:
this.radDateTimePicker1.Format = DateTimePickerFormat.Custom;
this.radDateTimePicker1.CustomFormat = "yyyy";
When trying to change the date, an ArgumentOutOfRangeException exception is thrown.
Here is how it looks at 200 % DPI: