How can I access windows that become inaccessible when using two displays? Description

When I connect a second display, InkScape windows aren't visible on either the primary or secondary display on any desktop. When I enter &amp; leave Mission Control, the InkScape windows fly off to the left towards the second display. Showing all windows (for XQuartz, as InkScape doesn't manage its windows) shows the window as belonging on the primary display (assigning it to the 2ary display doesn't make it accessible). When the second display isn't connected, the windows are accessible on the primary display. 
How can I access the InkScape windows with two displays?

Non-fixes

Assigning windows to desktops on either display (2ary click on app (XQuartz) in dock → Options → [Assign to] Desktop on Display x), or to all desktops (2ary click on app (XQuartz) in dock → Options → [Assign to] All Desktops) has no affect on window accessibility.

Other Info

"Displays Have Separate Spaces" is set in Mission Control preferences.

System Info

OS: 10.12.6 Sierra
As a workaround, rearranging the displays allows temporary access to the hidden windows. The windows can then be moved to (hopefully) make them accessible with the original display arrangement.


Open System Preferences
Open the "Displays" preferences
Click "Arrangement" tab
Move 2ndary display around primary display until the missing windows appear.
Move the (formerly missing) window to the primary display.
Move the 2ndary display back to the original position.


After restoring the display arrangement, the window may become inaccessible again; steps 4-6 may need to be repeated.