Atril remembers the last window position for the PDF file to open (incorrectly, though: Debian bug 978549). But when the monitor config changes, typically with a laptop when an external monitor is sometimes used, the window may appear almost completely off-screen (I suspect that it may appear completely off-screen). The consequence is that it is difficult, if not impossible, to retrieve the window. Atril should detect this issue and/or provide an option to ignore the last window position.