This 'invisible selected range' actually is empty label of check box editor. It exists in any our non-labeled check box editors on many property pages (for example see: '<Project Properties>=>Seam Settings=>Seam Support' check box or '<Project Properties>=>JBoss Tools Knowledge Base=>JBoss Tools Knowledge Base support' check box.
Standard concept in Eclipse is to place the label at right of check box. If the label is separated of the check box (and as such, the check box's label is empty) it's label is still shown at right (actually, the only placeholder is drawn).
Verified with JBDS 8.0.0.Beta1-v20140323-1410-B78