BeginGroup in WPF Devexpress Ribbon

Problem:
- I can't find "BeginGroup" in WPF Ribbon! is there any solution ...
- Does the silverlight ribbon bar items have the begingroup option? Can't find it anywhere.
- How do you do a BeginGroup in the application menu using WPF or SL ...

Solution:
Just used of a BarItemLinkSeparator in XAML instead of BeginGroup property.

XAML:
<dxr:RibbonPageGroup>
    <dxb:BarButtonItemLink BarItemName="barButtonItemFind" />
    <dxb:BarButtonItemLink BarItemName="barButtonItemBookmark" />
    <dxb:BarItemLinkSeparator />
    <dxb:BarButtonItemLink BarItemName="barButtonItemFirst"/>
    <dxb:BarButtonItemLink BarItemName="barButtonItemPrevious" />
    <dxb:BarButtonItemLink BarItemName="barButtonItemNext" />
    <dxb:BarButtonItemLink BarItemName="barButtonItemLast" />
</dxr:RibbonPageGroup>

The argument types 'Edm.Guid' and 'Edm.String' are incompatible

Error:
- The argument types 'Edm.Guid' and 'Edm.String' are incompatible for this operation. Near equals expression, line X, column Y.
- ObjectQuery<T>.Where problem with GUID
- Where filter predicate format is not match with GUID and ...

Solution:
The GUID format in where clause must be started with GUID term and covered with single quotation, like below

X.Where("it.ID = GUID'00000000-0000-0000-0000-000000000001'");

WPF Window Maximize problem

Problem
- The WPF application Maximize Problem and not work correctly
- The WindowState="Maximized" make window bigger than screen size and ...
- After loaded the window, it comes bigger than whole screen size and ...
- I created a WPF window and I'm running into maximizing problems.
- Problem in Maximize state
- Fully Maximize WPF Window using windowstate is not working

Solution
Just remove below line from XAML code.
SizeToContent="WidthAndHeight"
Or add below line after InitializeComponent(); in constructor

SizeToContent=System.Windows.SizeToContent.Manual;