What I am trying to do is show a window, that does not explicitly have a height/width, (both values omitted or set to Auto). I was guessing that the window wou
Auto
Old question but an updated answer:
As @Muad'Dib suggested in his answer :
you should set SizeToContent="WidthAndHeight".
SizeToContent="WidthAndHeight"
If the size of content of window increases more than the screen size, window can overflow from screen. So, you must consider:
MaxWidth="600" MaxHeight="400"