I downloaded the latest version of  MapViewer Editor the other day and double clicked the jar file and it opened right up.  But when I tried to connect to a server the dialog window opened behind the main program causing me to utter several phrases not appropriate for this post.

Turns out it’s just a java issue.  Whatever is in my path doesn’t point to what MapViewer Editor wanted to act right but instead of jacking around with Java home or path variables I just opened it from the command line telling it to use one of the many JDK’s living on my desktop.

Here’s the command I used just in case this saves someone else some pain.

"C:\Program Files\Java\jdk1.8.0_65\bin\java.exe" -jar map_editor-12.2.1.2.0.jar