OK, not 'another' answer, but part of the previous answer wink
I believe it came about with the 're-birth' of S-Z after the recent disaster ... if you put your cursor over the 'glass' it says "You are Watching This Topic" ... I think it only shows that if you have responded to that topic ...
Hope this helps ... smile
PS: When I first saw it I thought it was a tennis racquet ... ?!?!? confused1 laugh2
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t. cool