Canvas panel
A canvas panel is the simplest layout panel in Microsoft® Expression Blend™. It supports absolute positioning and does not apply any layout policy to its child elements—it is literally a blank canvas. Use a canvas panel when fixed positioning is paramount. Elements that you place in a canvas panel will not automatically resize when you resize your application as they can with a grid panel.
Add a canvas panel to a document by using the Asset Library 
or the layout container button
on the Toolbox.
