Use attached to reproduce.

Workaround:
Use date format that does not display the entire month name. 

Use the attached project and the following steps:
When the application starts, the entire content of the picker control is selected (which is fine).
Now press the Del key to clear the entire content.
If you then try and type in a date any key you type is shown briefly and is then cleared.
It is impossible to type anything until you open the drop down calendar and select something other than 1-1-0001.

Once another date is selected you can type normally.
Open the drop down calendar and select 1-1-0001 again and the same behavior occurs again.
This bug occurs whether or not ShowCheckBox is true.

Workaround:
- The NullDate should be different that the MinDate

 radDateTimePicker1.NullDate = DateTime.MinValue.AddDays(1);

Workaround:

class MyTextBoxInputHandler : TextBoxInputHandler
{

public MyTextBoxInputHandler(RadTextBoxControlElement el) : base(el)
{
}

public override bool ProcessMouseWheel(MouseEventArgs e)
{
return false;
}
}

 radTextBoxControl1.TextBoxElement.InputHandler = new MyTextBoxInputHandler(radTextBoxControl1.TextBoxElement);

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

        this.dateTimePicker = new RadDateTimePicker();
        this.dateTimePicker.DateTimePickerElement.Calendar.HeaderNavigationMode = HeaderNavigationMode.Zoom;
        this.Controls.Add(this.dateTimePicker);
    }
}

Workaround:
public partial class Form1 : Form
    {
        RadDateTimePicker dateTimePicker;
        public Form1()
        {
            InitializeComponent();

            this.dateTimePicker = new RadDateTimePicker();
            this.dateTimePicker.DateTimePickerElement.Calendar.PropertyChanged += Calendar_PropertyChanged;

            this.dateTimePicker.DateTimePickerElement.Calendar.HeaderNavigationMode = HeaderNavigationMode.Zoom;
            this.Controls.Add(this.dateTimePicker);
        }

        private void Calendar_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            if (e.PropertyName == "FocusedDate")
            {
                int year = this.dateTimePicker.DateTimePickerElement.Calendar.FocusedDate.Year;
                if (year <= this.dateTimePicker.MinDate.Year)
                {
                    this.dateTimePicker.DateTimePickerElement.Calendar.HeaderNavigationMode = HeaderNavigationMode.None;
                }
                else
                {
                    this.dateTimePicker.DateTimePickerElement.Calendar.HeaderNavigationMode = HeaderNavigationMode.Zoom;
                }
            }
        }
    }

Note: when you open the spell check dialog  and it iterates through the words, it does not highlight (select) the word in the linked RadTextBoxControl/RadTextBox, like it does in the Word's spell checker. 

One should be able to move to the next/previous word with Ctrl + right/left

The RadTokenizedTextItem should reference the data items as well. 

RadTextBox should indicate ReadOnly state

Add option to RadSpellChecker which will allow you to append the newly added words to the loaded dictionary and save them on the hard drive.

Add support for case sensitivity search in the suggested elements.

RadAutoCompleteBox - add functionality that allow you to show Popup without typing any char.

RadMaskedEditBox does not support G mask

Currently all spell checker dialogs are not accessible for customization.

first digit entered 3 would display 0.03
second digit 5 entered would display 0.35
third digit 0 entered  would display 3.50

Currently there can only be one delimiter in the autocomplete box. Different users might be accustomed to using different delimiters, even one user using several delimiters.

IMPROVE. RadTextBoxControl - add right to left support