Spoiler / Hidden Text

Hello,

I tried to use the boardsearch but it didn't come up with a thread so I guess it's the first time someone is asking for the possibility to hide text.

Example:

blah blah blah
[spoiler]
my hidden text
[/spoiler]
bleh bleh bleh

would become:

blah blah blah
(Button like) "Show hidden text"
bleh bleh bleh

It wouldn't be a problem to implement the button-like-thing but i dont know how to add own functions(buttons) to FCKeditor.

Any help?
Kind regards,
Chris