Hi,
I seem to have some trouble with the renderWith function

I have a DataObject and I created a public function that renders some data into a template and then returns the HTML, so I can use it to insert it in the TinyMCE via a widget.

public function getEventBlock()
{
      return $this->renderWith('Includes/EventBlock');
}

It works if I put the template in the mysite templates directory, but I like it to pull the template from the theme dir, so it will work with different themes.

I tried to use the full path the theme dir but that does not work
I tried this

public function getEventBlock()
{
$Template = new SSViewer();
$Template->setTemplateFile('themes/MyTheme/templates/Includes/EventBlock.ss');
return $this->renderWith($Template);
}

Any tips on how I can do this would be appreciated.

If you're trying to do this from the CMS, it won't work because the CMS has no theme.

thanks Pyromanik, Your right, if I call it from a template it is working fine.

But is there no way I can give it the full path to the template I want to use?

Well you shouldn't need to, but I think you can if it ends in .ss
http://api.silverstripe.org/3.1/source-class-SSViewer.html#765
&&
http://api.silverstripe.org/3.1/source-class-SSViewer.html#1064

No, just adding the .ss behind it did not work, but i found a solution, first you have to switch on the theme in SSViewer and than you assign the theme you like to the SSViewer that works

  public function getEventBlock()
  {
    Config::inst()->update('SSViewer', 'theme_enabled', true);
    Config::inst()->update('SSViewer', 'theme', 'MyTheme');
    $Template = new SSViewer('Includes/EventBlock');
    return $Template->process($this);
  }