How to reproduce:
Just open the popup with the Alt and Down arrow key combination, you will notice that the value changes

Workaround: 
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.radDateTimePicker1.DateTimePickerElement.KeyDown += DateTimePickerElement_KeyDown;
    }

    private void DateTimePickerElement_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.F4 || (e.KeyData == (Keys.Alt | Keys.Down)))
        {
            e.Handled = true;
        }
    }
}

Description:
RadMaskedEditBox (with MaskType=Numeric and Mask = "c") is bound to a property of type decimal. If you type in 15 it goes into the maskedEditbox as 51.

Reproduce:
-add a BindingSource (DataSource is set to some data table: for example "Products")
-add a BindingNavigator (Binding Source is set to the previously added bindingNavigator1)
-add a RadMaskedEditBox (with MaskType=Numeric and Mask = "c") with DataBindings: Value => bindingSource1 - UnitPrice
-add a new record using the yellow plus sign button in the navigator; get to the price field and just start typing your number: if you type in 15, it goes into the RadMaskedEditBox as 51.

Workaround:
Bind to Text instead of binding to Value of the RadMaskedEditBox

this.radMaskedEditBox1.DataBindings.Add(new Binding("Text", bindingSource1, "UnitPrice", true));

Resolution: 
RadMaskedEditBox with currency mask does not support null values. Default value must be 0 instead null. Please use the following code snippet: 
this.mePrice.DataBindings.Add(new System.Windows.Forms.Binding("Value", this.bindingSource1, "Price", true, System.Windows.Forms.DataSourceUpdateMode.OnPropertyChanged, 0, "C2"));

To reproduce:
-add a GridViewDateTimeColumn to a RadGridView.
-try to set RadDateTimeEditor.MaxValue in CellEditorInitialized event to 31/12/9999. As a result ArgumentOutOfRangeException("MaxDate cannot be higher than the max date") is thrown

To reproduce:
- add a RadMaskedEditBox with MaskType = MaskType.Standard
- input some numbers to fill all the expected digits
- select the content in the RadMaskedEditBox and press Enter key. As a result the last number is removed

Workaround:
private void radMaskedEditBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            e.Handled = e.KeyChar == (char)Keys.Return;
        }

Workaround: 

this.radTextBoxControl1.TextBoxElement.AutoCompleteDropDown.PopupOpening += AutoCompleteDropDown_PopupOpening;

private void AutoCompleteDropDown_PopupOpening(object sender, CancelEventArgs args)
{
    RadPopupOpeningEventArgs a = args as RadPopupOpeningEventArgs;
    if (a != null )
    {
        a.CustomLocation = new Point(a.CustomLocation.X,a.CustomLocation.Y + 20);
    }
}

To reproduce:
1. Add a RadTextBox
2. Set the AutoCompleteMode property to SuggestAppend 
3. Add a RadSpellChecker and set the AutoSpellCheckControl property  the text box
4. Start typing. You will notice that the autocomplete functionality behaves as expected. But the incorrect words are not underlined. 

Workaround:  use RadTextBoxControl

Add IME support to RadTextBoxControl and RadAutoCompleteBox.

To reproduce:

public Form1()
{
    InitializeComponent();
    this.radAutoCompleteBox1.AppendText("abc;");
}

Workaround: append the text in the Form.Load event.

private void Form1_Load(object sender, EventArgs e)
{
    this.radAutoCompleteBox1.AppendText("abc;");
}

To reproduce:
-add RadDateTimePicker and apply Windows7 theme
-enable calendar footer
-when opening the drop down calendar, the date part in the footer is not displayed correctly

Workaround:
 RadDateTimePickerCalendar calendarBehavior = 
     this.radDateTimePicker1.DateTimePickerElement.GetCurrentBehavior() as RadDateTimePickerCalendar;
 RadCalendar calendar = calendarBehavior.Calendar as RadCalendar;
 calendar.ShowFooter = true;
 calendarBehavior.PopupControl.PopupOpening += PopupControl_PopupOpening;

private void PopupControl_PopupOpening(object sender, CancelEventArgs args)
{
    RadDateTimePickerDropDown popup = sender as RadDateTimePickerDropDown;
    if (popup != null)
    {
        popup.Height = 250;
        popup.Width = 280;
    }
}

To reproduce:
-add a RadTimePicker;
-change its culture:
this.radTimePicker1.Culture = new System.Globalization.CultureInfo("en-GB");

Workaround:
public Form1()
{
    InitializeComponent();

    this.radTimePicker1.Culture = new System.Globalization.CultureInfo("en-GB");
    this.radTimePicker1.TimePickerElement.PopupForm.Height =350;
   
}

The performance can be improved by creating the RadContextMenu only when it is needed not when the element is created.

To reproduce:
 this.radDateTimePicker1.MaxDate = DateTime.Today;
private void radButton1_Click(object sender, EventArgs e)
{
    this.ValidateChildren();
}

Workaround:
this.radDateTimePicker1.MaxDate = new DateTime( DateTime.Today.Year,DateTime.Today.Month,DateTime.Today.Day, 23,59,59);

To reproduce:
public Form1()
{
    InitializeComponent();

    this.radTextBox1.Text = "abcd";
    this.radTextBox2.Text = "abcd";
    this.radTextBoxControl1.Text = "abcd";
    this.radTextBoxControl2.Text = "abcd";

    this.radTextBox2.Multiline = true;
    this.radTextBoxControl2.Multiline = true;

    this.textBox1.Text= "abcd";
    this.textBox2.Text= "abcd";
    this.textBox2.Multiline = true;
}

Workaround: set the Multiline property to true in the Form.Load event.

Second workaround: this.radTextBox2.TextBoxElement.TextBoxItem.Margin = new Padding(-2, 0, 0, 0);

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);

To reproduce:
- Set the font for all dates.
- Zoom In and out.

Workaround:
Use the ZoomChanged event and change the font while one zooms as well.

Workaround:
1) set the CurrencyNegativePattern to 1
Alternatively:
2) check if the the formatted text is surrounded with brackets and if yes set the value of the masked edit box to be negative

To reproduce:
public RadForm1()
{
    InitializeComponent();

    this.radTextBoxControl1.Text = "Sample text with misspelledd word";
    RadSpellChecker spellChecker1 = new RadSpellChecker();
    spellChecker1.AutoSpellCheckControl = radTextBoxControl1;
}

private void radTextBoxControl1_ContextMenuOpening(object sender, TreeBoxContextMenuOpeningEventArgs e)
{
    RadMenuItem customItem= new RadMenuItem("Custom item");
    e.ContextMenu.Items.Add(customItem);
}

Workaround: use RadTextBox instead:
RadSpellChecker spellChecker1 = new RadSpellChecker();    
this.radTextBox1.Text = "Sample text with misspelledd word";
spellChecker1.AutoSpellCheckControl = this.radTextBox1;
TextBoxSpellChecker tbSpellChecker = spellChecker1.GetControlSpellChecker(typeof(RadTextBox)) as TextBoxSpellChecker;
tbSpellChecker.DropDownMenu.DropDownOpening += DropDownMenu_DropDownOpening;

private void DropDownMenu_DropDownOpening(object sender, CancelEventArgs e)
{
    RadDropDownMenu menu = sender as RadDropDownMenu;
    RadMenuItem customItem = new RadMenuItem("Custom item");
    menu.Items.Add(customItem);
}

To reproduce:

Place a MaskedTextBox on a Form
Set 'MaskType' to 'Numeric' (and in my case I have Mask set to 'D' to allow integer values only)
Run the application / open the form - by default the masked textbox has a value of '0'
Elsewhere (i.e. notepad) enter and copy a text like 'CT_1234' into the clipboard (please note the starting non-numeric string characters)
Go back to the application / form and click into the masked text box
Select the pre-existing value (by default  the '0' mentioned above or any other value i.e. '11111' .. and by select I mean via mouse or [Shift]+[Arrow Key Left/Right])
Press [Ctrl+V]
>> Nothing happens
.. what should happen though is that the selected text is overridden with '1234'
However, if you have no text selected in the masked text box and place the cursor in it i.e. at the very beginning or end of the existing value, pasting works as expected.. the value '1234' is added (and correctly 'dropping the 'CT_' in front of it).

Workaround: 
((StackLayoutElement)this.radBrowseEditor1.BrowseElement.Children[2]).ShouldHandleMouseInput = false;
this.radBrowseEditor1.BrowseElement.TextBoxItem.RouteMessages = true;