I can't get the backuplist+ window to hide.

I set the preferences to have it show up as an icon in the menu bar. I quit and relaunched it. But the main window cannot be hidden. With the window active, I option-click the Desktop, and although the backuplist+ window is in the background, it won't hide. I click on the Desktop with Option-Cmd pressed and everything else hides, but not backuplist+.

The best I can do is to drag it so it is almost off-screen. Am I missing something in the configuration?