Where is the problem?

[RD]

Python 3.4.3 on WinXP.

I create a Tk canvas and draw on it with create_text(), 
create_line(), and create_polygon with fill and stipple.

So far, so good, looks fine on the screen.

So I go to send it to a postsctript file:

bmap.postscript(file="tmp.ps", colormode='color')

It generates a file, no errors reported.

So I open up the file in a PS viewer (2, actually),
and the saved file looks like someone left a 
watercolor out in the rain.

Artifacts everywhere, the lines are blurred, and the 
text is unreadable.

Googling was unhelpful; did I miss something?

TIA