To reproduce:
- Use the following format:
radDateTimePicker1.Format = DateTimePickerFormat.Custom;
radDateTimePicker1.CustomFormat = "MM/dd/yyyy";

- Clear the date and try to enter 01/01/2017 (see attched video) 

Workaround:
 radDateTimePicker1.NullDate = DateTime.MinValue.AddYears(1);

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);

Please refer to the attached sample project and attached gif file which illustrates the desired behavior when RadForm1 is run. If you run RadForm2 which uses RadDropDownList, the binding doesn't work as expected.

Workaround:
this.radDropDownList1.SelectedIndexChanged += RadDropDownList1_SelectedIndexChanged;
this.radDropDownList1.DisplayMember = "Naziv";
this.radDropDownList1.ValueMember = "Id";
this.radDropDownList1.DataSource = bs;

private void RadDropDownList1_SelectedIndexChanged(object sender, 
    Telerik.WinControls.UI.Data.PositionChangedEventArgs e)
{
    if (e.Position > -1)
    {
        Roditelj parent = this.radDropDownList1.SelectedItem.DataBoundItem as Roditelj;
        this.radDropDownList2.DataSource = null;
        this.radDropDownList2.DisplayMember = "Naziv";
        this.radDropDownList2.ValueMember = "Id";
        this.radDropDownList2.DataSource = parent.Djeca;
    } 
}

Please refer to the attached sample project and try to open the form's designer. If you comment  [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] for the EditarTextBox property (typeof(RadTextBox)), clean and rebuild, the designer is opened as expected.

Workaround: use RadTextBoxControl.

To reproduce:

this.radDateTimePicker1.ThemeName = "TelerikMetroTouch";
var calendar1 = (radDateTimePicker1.DateTimePickerElement.CurrentBehavior as RadDateTimePickerCalendar);
calendar1.ShowTimePicker = true;

Workaround:

calendar1.Calendar.Width = 250;
calendar1.DropDownMinSize = new System.Drawing.Size(500, 250);

Please refer to the attached screenshot.

Workaround: Me.RadDateTimePicker1.DateTimePickerElement.TextBoxElement.MaxSize = New Size(0, 20)

To reproduce:

ThemeResolutionService.ApplicationThemeName = "Office2013Light";
this.radTextBox2.Enabled = false;
 
Workaround:             this.radTextBox2.BackColor = Color.LightGray;

To reproduce:
- Add RadMaskedEditBox to a form.
- Set AutoSize to false.
- Set the height of the control to 30.

Workaround:

radMaskedEditBox1.AutoSize = false;
radMaskedEditBox1.MaskedEditBoxElement.TextBoxItem.MinSize = new Size(0, 30);

Workaround: increase the height:

this.radTimePicker1.MinimumSize = new Size(0, 28);

Workaround:
public Form1()
{
    InitializeComponent(););

    this.richTextBox1.Text = "thess is is a tesssset";

    this.radSpellChecker1.AutoSpellCheckControl = this.richTextBox1;
    this.radSpellChecker1.SpellingFormShowing += radSpellChecker1_SpellingFormShowing;
}

private void radSpellChecker1_SpellingFormShowing(object sender, SpellingFormShowingEventArgs e)
{
    e.SpellingForm.FormClosed -= SpellingForm_FormClosed;
    e.SpellingForm.FormClosed += SpellingForm_FormClosed;
}

private void SpellingForm_FormClosed(object sender, FormClosedEventArgs e)
{
    this.radSpellChecker1.AutoSpellCheckControl = null;
    this.radSpellChecker1.AutoSpellCheckControl = this.richTextBox1;
}

How to reproduce:
 public RadForm1()
 {
     InitializeComponent();

     this.radDateTimePicker1.Format = DateTimePickerFormat.Custom;
     this.radDateTimePicker1.CustomFormat = "MM/dd/yyyy";
     this.radDateTimePicker1.DateTimePickerElement.Calendar.HeaderNavigationMode = Telerik.WinControls.UI.HeaderNavigationMode.Zoom;
     ((Telerik.WinControls.UI.MaskDateTimeProvider)this.radDateTimePicker1.DateTimePickerElement.TextBoxElement.Provider).AutoSelectNextPart = true;
 }

Workaround:
 public RadForm1()
 {
     InitializeComponent();

     this.radDateTimePicker1.Format = DateTimePickerFormat.Custom;
     this.radDateTimePicker1.CustomFormat = "MM/dd/yyyy";
     this.radDateTimePicker1.DateTimePickerElement.Calendar.HeaderNavigationMode = Telerik.WinControls.UI.HeaderNavigationMode.Zoom;
     ((Telerik.WinControls.UI.MaskDateTimeProvider)this.radDateTimePicker1.DateTimePickerElement.TextBoxElement.Provider).AutoSelectNextPart = true;

     this.radDateTimePicker1.DateTimePickerElement.TextBoxElement.KeyDown += TextBoxElement_KeyDown;

 }

 private void TextBoxElement_KeyDown(object sender, KeyEventArgs e)
 {
     RadMaskedEditBoxElement tb = (RadMaskedEditBoxElement)sender;
     MaskDateTimeProvider provider = (MaskDateTimeProvider)tb.Provider;

     switch (provider.List[provider.SelectedItemIndex].type)
     {
         case PartTypes.Month:
             if (e.KeyCode == Keys.Left)
             {
                 provider.SelectedItemIndex = provider.List.Count;
             }

             break;
         case PartTypes.Year:
             if (e.KeyCode == Keys.Right)
             {
                 provider.SelectedItemIndex = -1;
             }
             break;
     }
 }

All controls (i.e. RadGridView, RadPropertyGrid, etc.), which use textbox editor, containing HostedTextBoxBase descendant, can be spelled by the RadSpellChecker. But the red underline is not displayed entirely. The inside hosted text box should have a bigger height.

To reproduce: 

Populate the AutoCompleteBox and start a search returning enough results to need the scrollbar. When clicking and dragging the scroll bar to scroll - if the cursor is not positioned directly over the scrollbar at the time you release the mouseclick, the dropdown list is closed an item is added to the selection.

Workaround: 
 public partial class Form1 : Form
    {
        bool isMouseDown = false;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            AddAutoCompleteItems();
            radAutoCompleteBox1.ListElement.VScrollBar.MouseDown += ListElement_MouseDown;
            radAutoCompleteBox1.ListElement.VScrollBar.MouseUp += ListElement_MouseUp;
            radAutoCompleteBox1.TokenValidating += radAutoCompleteBox1_TokenValidating;
        }

        void radAutoCompleteBox1_TokenValidating(object sender, TokenValidatingEventArgs e)
        {
            e.IsValidToken = !isMouseDown;
            isMouseDown = false;
        }

        void ListElement_MouseUp(object sender, MouseEventArgs e)
        {
            RadListVisualItem el = radAutoCompleteBox1.ListElement.ElementTree.GetElementAtPoint(e.Location) as RadListVisualItem;

            if (el != null)
            {
                return;
            }
            
            isMouseDown = false;
        }

        void ListElement_MouseDown(object sender, MouseEventArgs e)
        {
            isMouseDown = true;
        }

        private void AddAutoCompleteItems()
        {
            RadListDataItemCollection items = this.radAutoCompleteBox1.AutoCompleteItems;

            items.Add(new RadListDataItem("Joe Smith", "joe@fakecompany.com"));
            items.Add(new RadListDataItem("Adam Petersen", "adam@qwerty.com"));
            items.Add(new RadListDataItem("Jack Russel", "jack@russel.nocom"));
            items.Add(new RadListDataItem("Daniel Finger", "daniel.pinger@gmail.com"));
            items.Add(new RadListDataItem("Richard Vail", "rvail@richardvail.com"));
            items.Add(new RadListDataItem("Sebastian Jonnson", "s.jonnson@sjonnson.com"));
            items.Add(new RadListDataItem("Lee Cooper", "lee.cooper@coopercoorp.com"));
            items.Add(new RadListDataItem("Kelvin Clain", "kclain@clainkevin.com"));
            items.Add(new RadListDataItem("Maria Jenson", "mjenson@mariajenson.com"));
            items.Add(new RadListDataItem("Chelsea Maarten", "chelsea@maarten.com"));
            items.Add(new RadListDataItem("Jenson Chew", "jenson.chew@nospam.com"));
            items.Add(new RadListDataItem("Martin Williams", "m.williams@martinandwilliams.com"));
            items.Add(new RadListDataItem("Telerik", "clientservice@telerik.com"));
            items.Add(new RadListDataItem("James Stone", "james.stone@manystones.com"));
            items.Add(new RadListDataItem("Samuel Jackson", "samuel.jackson@nojackson.com"));
        }
    }

    public class MyRadAutoCompleteBox : RadAutoCompleteBox
    {
        protected override RadTextBoxControlElement CreateTextBoxElement()
        {
            return new MyRadAutoCompleteBoxElement();
        }
    }

    public class MyRadAutoCompleteBoxElement : RadAutoCompleteBoxElement
    {
        protected override TextBoxViewElement CreateViewElement()
        {
            return new MyAutoCompleteBoxViewElement();
        }

        protected override Type ThemeEffectiveType
        {
            get
            {
                return typeof(RadAutoCompleteBoxElement);
            }
        }
    }

    public class MyAutoCompleteBoxViewElement : AutoCompleteBoxViewElement
    {
        protected override int InsertTokenizedTextBlocks(int index, string text, bool performInvalidation)
        {
            bool isValid = performInvalidation ? this.OnTokenValidating(text) : true;

            if (!isValid)
            {
                return index;
            }
            return base.InsertTokenizedTextBlocks(index, text, performInvalidation);
        }

To reproduce:
- Select the time from the drop down and press close button.
- Notice that the form is deactivated.

Workaround:
void radTimePicker1_LostFocus(object sender, EventArgs e)
{
    this.Activate();
}

To reproduce:
this.radTextBoxControl1.Text = "dog and blue glue";
this.radTextBoxControl1.Size = new Size(50, 65);
this.radTextBoxControl1.Multiline = true;

Workaround:
use RadTextBox.

Multiply line text is not correct align at the left side when control runs on Win xp.

Steps to reproduce:
this.radTextBoxControl1.Text = "This\nis a\ntest";

To reproduce:

1. Please refer to the attached sample project.
2. Run the project and click the button. The two RadTextBox controls are left aligned.
3. Close the opened form and click the button again. You will notice that the RadTextBox is not left aligned.

Workaround: use RadTextBoxControl.

To reproduce:
- Add RadtextBox to a form and anchor it to the left and right.
- Set WindosState of the form to Maximized
- Start the application

Workaround
void RadForm1_Shown(object sender, EventArgs e)
{
    this.WindowState = FormWindowState.Maximized;
}

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);
}