To reproduce:

Add an mdi child to a form:

this.IsMdiContainer = true;
new Form
{
    MdiParent = this
}.Show();

ThemeResolutionService.ApplicationThemeName = new VisualStudio2012DarkTheme().ThemeName;

Start the application and maximize the child form. You will see that there is no status bar for the child form. The same behavior occurs with the VisualStudio2012LightTheme.

Workaround:

You need to set images to the buttons in the title bar:

this.FormElement.MdiControlStrip.MinimizeButton.Image = this.FormElement.TitleBar.MinimizeButton.Image;
this.FormElement.MdiControlStrip.MaximizeButton.Image = this.FormElement.TitleBar.MaximizeButton.Image;
this.FormElement.MdiControlStrip.CloseButton.Image = this.FormElement.TitleBar.CloseButton.Image;


this.FormElement.MdiControlStrip.MinimizeButton.ShowBorder = this.FormElement.MdiControlStrip.MaximizeButton.ShowBorder = this.FormElement.MdiControlStrip.CloseButton.ShowBorder = false;

To reproduce:

Create a RadPropertyGrid and set its SelectedObject. Set the theme to VisualStudio2012Light, change a property of the selected object and select another property, you will see that the previous property is selected. Now scroll until the previous property is no longer visible, now scroll back until it is visible, you will see that the selection is gone. By design this selection should not exist at all.

Workaround:

Open the theme with VisualStyleBuilder => RadPropertyGrid => PropertyGridElement => PropertyGridTableElement => PropertyGridItemElement and set the FillTransparent repository to the PropertyGridItemElement.IsModified state.

Happens with Win8 and VS2012 themes, but not with the Office themes only with form's top left and right corners. If the mouse is moved into the corner from the center of the form. From this cursor position, the form cannot be resized.  From this position, once a resize is attempted, repositioning the mouse and retrying the resize may not work at all.

If you dock a control in RadPanel, this control will cover the borders of RadPanel. This behavior is different from the behavior of the standard Panel behavior where the border is not covered, because of a Padding of 1.

We should consider whether this change should be introduced in our suite as this could modify the design of our customers' layouts in a way then don't want.

Workaround: this.radPanel1.Padding = new Padding(1);

If set ClickMode to Press after that the buttons stay howered

Steps to reproduce:
Place a RibbonBar with one RadButtonGroup with few ButtonElements
Set the PressMode in Form constructor.
public Form1()
{

            foreach (RadButtonElement item in radRibbonBarGroup1.Items)
            {
               item.ClickMode = Telerik.WinControls.ClickMode.Press;             
            }
}

Workaround: 
void item_Click(object sender, EventArgs e)
{
    ((RadButtonElement)sender).SetValue(RadButtonElement.IsMouseDownProperty, false);
}

To reproduce:

string filePath = @"D:\Projects\1015954MenuItemHTML\1015954MenuItemHTML\Resources\calendar.png";
StringBuilder sbItem = new StringBuilder();
sbItem.Append("<html><b>aaa<img src=" + filePath + ">");
sbItem.Append("</html>");

RadMenuItem item = new RadMenuItem();
item.Text = sbItem.ToString();
this.radMenuItem1.Items.Add(item);


Workaround: use resource file: string filePath = @"res:_1015954MenuItemHTML.Resources.calendar.png";

To reproduce:
1. Drag and drop RadCheckBox and RadRadioButton on the form
2. Set the Checked/IsChecked property to true. 
this.radCheckBox2.Checked = true;
this.radRadioButton2.IsChecked = true;
3. Apply the Office2013Light theme  
4. On button click set the Enabled property to false. 
The ForeColor is different when disable checked item and unchecked item(see attached image - RadCheckBox_Disable_Checked.png). 

Workaround: 
Apply custom StateManager of RadCheckBox/RadRadioButton. 
In the attachments can be found sample demo with all necessary modifications. 

Switch button (On/Off) similar to the switch button that can be found on most smartphones nowadays. This button should have a caption and it will be nice if it supports three states.

To reproduce: 
1. Install Telerik UI for WinForms Q3 2015 SP1 or Q1 2016 trial version 
2. Open Demo Application and navigate to RichTextEditor examples 
3. Click on tile First Look and you will see the exception 

Workaround: 
Open the solution RichTextEditor from folder Examples. The location where can be found is: C:\Program Files\Telerik\UI for WinForms [Version]\Examples\RichTextEditor

How to reproduce: 
Add a RadDropDownListElement to a RadRibbonBar and set its ToolTipText property. The tool tip is not displayed because the hover event is consumed by a child element having an empty ToolTipText 

Workaround:
Handle the ToolTipTextNeeded event

Currently there is no such component in RadControls for WinForms

Resolution: In Q2 2014 we introduced Spread Processing which use the RadSpreadProcessing library. You can refer to our help documentation for more information. Here the link http://www.telerik.com/help/winforms/spreadprocessing-overview.html 

Let's have two controls - RadLabel and RadCheckBox and a form, anchored to Bottom, Right. Show a form containing these controls in maximized mode and you will notice that the controls' location is not correct.

FIX. RadRibbonForm - exception when loading icon in design time "Requested range extends past the end of the array."

ApplicationButton and QuickStartToolbar layout do not look good when user changed the theme in runtime.
Issue can be reproduced with Office2010Silver, Deser, HighContrastBlack and Windows7 themes.

Workaround:
 call recursively the UpdateLayout method for all RadControls in the form:

ThemeResolutionService.ApplicationThemeName = item.Text;
    this.RefreshAll();
    m_strThemeName = item.Text;
    SaveThemeName();
...
}
 
private void RefreshAll()
{
    foreach(Control control in this.Controls)
    {
        RefreshAllControls(control);
    }
}
 
void RefreshAllControls(Control ctrl)
{
    foreach (Control control in ctrl.Controls)
    {
        RadControl radControl = control as RadControl;
        if (radControl != null)
        {
            radControl.RootElement.InvalidateMeasure(true);
            radControl.RootElement.UpdateLayout();                   
        }
        RefreshAllControls(control);
    }
}

Description: Control wich allows to design a flow chart. Where every node could have a different image and assume properties of custom objects. Same thing for every link between nodes.
http://www.telerik.com/help/wpf/raddiagram-overview.html