'Teaser Break' Button missing

Because, if you select NO button in the configuration, the editor uses HIS own default button configuration.

But the teaser break button is Drupal specific, so you need to activate this button explicitly. BUT this will override the default configuration from the editor, so you need to explicitly activate every button you wanna have.

Hope that helps.

What worldwidemv said is correct. This is currently by design. Please see #735624: Enabling one button removes default editor toolbar for a related discussion.

I understand that this is by design. However - this is a very important button and should be part of a default from my usability perspective.
Is it possible to edit the ckeditor own button definition to show teaser break button also?
(Is this in the libraries/ckeditor?)

BTW: Is the code to support the teaser break implemented in the editor itself or is this wysiwyg code? Will the button eventually work different if added directly?)

We might check the approach of #751196: Width of input area in CKEditor #8 for modifying the buttons.

Hey, Miro check the Comments down below here : http://drupal.org/node/829266 .. so its part of the CKeditor API.

We will not include Teaser Break or any other plugin in the editor's own default toolbar layout as we won't modify the library files and need it intact for debugging purposes. However, as part of #735624: Enabling one button removes default editor toolbar it's likely that showing the editor's default toolbar will be a hidden setting and we'll show some other layout by default. As the request is now to change the default layout shown to the user, I'm marking this a duplicate of #735624: Enabling one button removes default editor toolbar. Please read through that issue and follow up on that discussion if you have something to add.