Steps to reproduce:

Create new Telerik Windows Forms Application ( I use VB.net but this crashes in C# as well )

Create RadRibbonForm - set the Project so this is the Startup Form.

Add Office2013LightTheme to form.

Set RadRibbonBar1.ThemeName to Office2013LightTheme.

Set ApplicationMenuStyle property = BackstageView

Run the ap, click on the Backstage tab and you'll see the first Image attached (called First.png)

Close the ap and back to Visual Studio - with the Form open in the Designer.

Everything is set but now i want to change the Background color of that lovely blue panel and everything inside it to a new background color.

I'd like to do this without creating a new Theme.

Click on the little triangle thingie in the upper right corner and select "Edit UI Elements"

Look down the Tree until you see BackstageItemsPanelElement.

Set BackstageItemsPanelElement.BackColor = 64, 53, 130

Close the Edit UI Elements dialog box and save then Start.  

Open the Backstage and you can see the "Back Button" at the very top still has the blue backcolor (No clue why this object doesnt get it's background from its Parent but it does not) so lets fix the background color for that button.

Close the Ap if its still running.  Open the form in VS Designer.  Edit UI Elements.  Look down until you find this:

RootRadElement.BackstageViewElement.BackstageItemsPanelElement.RadButtonElement.FillPrimitive

Set RadButtonElement.FillPrimitive.BackColor = 64, 53, 130

and we have to get the border - found under the RadButtonElement.BorderPrimative.FORECOLOR

Set RadButtonElement.BorderPrimative.ForeColor = 64, 53, 130

Close Element hierarchy editor.  Save and Run.

Everything looks great now right!??  Attached image #3 (Second.png)

If you examine form.designer.vb you will see these three lines have been added:

This is the BackstageItemsPanelElement.Backcolor we changed:

CType(Me.myBackStage.GetChildAt(0).GetChildAt(2), Telerik.WinControls.UI.BackstageItemsPanelElement).BackColor = System.Drawing.Color.FromArgb(CType(CType(64, Byte), Integer), CType(CType(53, Byte), Integer), CType(CType(130, Byte), Integer))

This is the Back Button's FillPrimitive we changed (NOTE Indexes 0, 2, 0, 0)

CType(Me.myBackStage.GetChildAt(0).GetChildAt(2).GetChildAt(0).GetChildAt(0), Telerik.WinControls.Primitives.FillPrimitive).BackColor = System.Drawing.Color.FromArgb(CType(CType(64, Byte), Integer), CType(CType(53, Byte), Integer), CType(CType(130, Byte), Integer))

And this is the Back Button's BorderPrimitive we changed (NOTE Indexes 0, 2, 0, 2)

CType(Me.myBackStage.GetChildAt(0).GetChildAt(2).GetChildAt(0).GetChildAt(2), Telerik.WinControls.Primitives.BorderPrimitive).ForeColor = System.Drawing.Color.FromArgb(CType(CType(64, Byte), Integer), CType(CType(53, Byte), Integer), CType(CType(130, Byte), Integer))

And now to the CRASH.

Close the ap if still running. 

Open the form in Designer. 

Switch to Backstage. 

Click on the triangle thing again and this time Click on "Add Tab Item"

Save your form.

Close the form (Designer)

Now try to reload the form in the Designer.

CRASH!!!

You get a Dialog that i believe the Ribbon is throwing (Or more precisely the Backstage object) that says "Error parsing RadItem:  Children collection index is not valid: 0 - 2 - 0 - 0" - See attached image "Crash.png" - this is followed by another almost identical error dialog box except this one will say "0 - 2 - 0 - 2" 

Those three lines i posted above that were added to the form.Designer.vb code the first one is fine and has no issues.  The next two lines however are what's causing the problems (FillPrimitive and BorderPrimitive)

Any help anyone can offer would be very very appreciated at this time.  I've spent two days trying to work this out.  If there's no way to fix this can anyone suggest an alternate way for me to change those background colors without altering the Theme? 

Cheers all!