Re: import -frame doesn't get the window contents

> I often end up with a png that includes a layer
> offset

Try

  import +repage -screen -frame screen.png

> Sometimes it shows portions of the window
> as black

The import program asks the X11 server for the pixels inside a window.  In
some cases these pixels may not be defined to X11, for example, OpenGL uses
X11 to define a window but bypasses X11 when it renders the pixels inside the
Window.  However, if you use the xwd program and it saves the window pixels
properly and the import program does not it could very well be a bug in the
import program.