Edit function in the +More options (how long is it available?)

When posting on the forums, I have noticed that there's an edit "function" as part of the "+More options" at the bottom. I know I can use that edit function immediately after posting, but have found that its gone after a while. Does someone know for how long this edit function lasts??

Have tried a search, but unsuccesfull alas....

--
Best regards, Marius
@ Panasonic's Mr Ichiro Kitao, I support the call to upgrade the FZ50 (and the famous FZ30 before it) using many of the excellent improvements made available in the FZ200 and adding the extra's for making it the real thing (the FZ250?!.
I will definitely buy one as this will then be the digital superzoom I have been wanting for years!!!