The toolbar spec is defined in sapphire/forms/HtmlEditorField.php - there's a class HtmlEditorField_Toolbar.

Yes, you can, but it will require a fair bit of mucking around:

1) Apply this changeset to your own copy. This will appear in the next version, so you're not distrupting upgradeability.

http://open.silverstripe.com/changeset/53459/modules/cms/trunk/code/LeftAndMain.php

2) Create MyToolbar.php. Overload any methods that you need to:

class MyToolbar extends HtmlEditorField_Toolbar {

}

3) Add the following to _config.php:

Object::useCustomClass("HtmlEditorField_Toolbar", "MyToolbar");

If someone wants to write a patch that defines methods such as these, that would be handy.

HtmlEditorField_Toolbar::set_controls($controls);
HtmlEditorField_Toolbar::add_control($control, $row, $insertBefore = null);
HtmlEditorField_Toolbar::remove_control($control);

You would then be able to use these methods to amend the toolbar without creating a new class.

Those last 3 methods don't currently exist, it's a feature suggestion for anyone who wants to implement them.

It seems to me, that it does not work anymore in SIlverstripe 2.2.2

Any ideas, bugfixes?