munghauzen, надо добавить кнопку вручную через админку:
Go to: BB Code
1-click on:Make new one
2-
Titel: hide
bb code: hide
Replacement: [hide]{param}[/hide]
Example: [hide]www.wheretohide.com[/hide]
Use {option}: yes
Write the path properly to your hide button >> example: images/buttons/hide.gif
At last make yes to the first 4 and no to the last en apply.
Now your botton is online in the editor again.