A: 

Try this:

int height = (int)border.ActualHeight;
int width = (int)border.ActualWidth;
RenderTargetBitmap bmp = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Pbgra32);
bmp.Render(border);

border being what you're trying to save as bitmap.

Gustavo Cavalcanti
Thanks for the tip. ActualHeigth and ActualWidth make sense. Unfortunately in this case it is not making a difference.
Julio Garcia
And you're using 96, 96 right?
Gustavo Cavalcanti
A: 

Ok, I finally found a solution. Gustavo you were on the right track. The problem was that the main container that I was trying to render as bitmap was being distorted by its parent container. The solution was to add the main container to a canvas, that doesn't have a layout engine that distorts its children. I still need to do some more experimenting but it looks very promising. Apparently RenderTargetBitmap doesn't like distorted fonts at all.

Julio Garcia