Hello Alex,
In my opinion you do not have to use Microsoft Expression Blend for that purpose.
Actually you have a variety of options here.
For example you may define a simple Border as follows, no matter horizontal/vertical:
You may adjust those according to the desired layout of your application.
On the other hand you may also use a
GridSplitter for that purpose.
Regards,
Vanya Pavlova
the Telerik team