I am trying to add buttons to the backend toolbar, similiar to the buttons 'New', 'Edit', 'Mass Mail' etc.

I did find a 'custom function' which seemt to do exactly what I need:
[code:1]* Writes a custom option and task button for the button bar
* @param string The task to perform (picked up by the switch($task) blocks
* @param string The image to display
* @param string The image to display when moused over
* @param string The alt text for the icon image
* @param boolean True if required to check that a standard list item is checked
*/
function custom( $task='', $icon='', $iconOver='', $alt='', $listSelect=true, $prefix='' ) {
if ($listSelect) {
$onClick = "if (document.adminForm.boxchecked.value == 0){
alert('" . addslashes( sprintf( CBTxt::T('Please make a selection from the list to %s'), $alt) )."');
}else {
".$prefix."submitbutton('$task');
}";
} else {
$onClick = $prefix . "submitbutton('$task')";
}
// if ( $icon ) {
$icon = preg_replace( '/\.[^.]*$/', '', $icon );
echo cbMenuBarBase::_output( $onClick, $icon, $alt );
// }
}
[/code:1]

But I could not find a trigger for utilizing this function in any way. Before searching endlessly I am wondering if it is even possible without core hacking. Maybe somebody has a hint for me or a code example.

Thanks for your info. I think that helped to grasp that concept. However that strengthened my impression that this is only for the creation of new plugins.
I cannot imagine to simply add new buttons to the exising CB core component, mainly the user manager.
What I would like to achieve are additional buttons in the CB User Manager toolbar. I wonder if there is a way to create a plugin which simply does that without hacking the core.

Ok. Thanks.
Maybe you have another idea to achieve what I am looking for?
Manually approving members can be a pain in a large community. I was looking for a mass solution:
Checking the check box of the users which should be approved and then clicking 'Approve' once only.
Otherwise it is a pain as the complete page refreshes everytime after approving or disapproving a user.

So what I am looking for is a mass action for approving/rejecting users. I thought this would fit perfectly into the toolbar. But maybe you have another idea to achieve this without hacking the core?