not reachable with tab traversal

Steps To Reproduce:
goto file wisdl, Services, file address and right click for properties sheet
run Accessibilty test tool on the properties sheet


Observation:
Results of Accessibility test, window with title "file:address - Properties"


 Doesn't implement Accessible :
   - none.

 No Accessible name :
   - none.

 No Accessible description :
   - none.

 Label with LABEL_FOR not set :
   - none.

 Components with no LABEL_FOR pointing to it :
   Class: org.openide.explorer.propertysheet.SheetTable {  Properties table |  Table of editable properties 
representing the current object } 


 Components with no mnemonic :
   - none.

 Components with wrong mnemonic (mnemonic isn't ASCII , label doesn't contain mnemonic):
   - none.

 Components not reachable with tab traversal :
   Class: org.openide.explorer.propertysheet.SheetTable {  Properties table |  Table of editable properties 
representing the current object }