Hans, please try to run the Editor from the command line:
- run [font=courier new]cmd[/font]
- type [font=courier new]java -jar[/font] and drag and drop FurnitureLibraryEditor-1.18.jar file in the command window to get its path
- type <Enter>.

If there's a problem, there should be some log that appears in the command window. Please report it here, so I can help you further.