FCKeditor 2 is incompatible with the current beta of Firefox 17 (b4). Firefox 17 is due for release on November 20. Things could change between now and the release in two weeks, but depending on this old, unsupported version of the FCKeditor in the Text & Picture component carries increasing risk with each new browser version.
"Thanks for the info but FF17 is a beta (I presume, since 16 is the latest version). Mozilla might fix the issue before the official release. We also don't maintain FCKeditor anymore. We've been telling people to upgrade for the last two years because every new browser update creates the risk of potential bugs."
Customer and Community Manager, CKSource
Yup! The FCK in Roxen does not work with Firefox 17.