Magento add wysiwyg editor in custom module.

step-1

Go to following path and open Edit.php

app\code\local\Namespace\Modulename\Block\Adminhtml\Modulename\Edit.php

and Add this Function


protected function _prepareLayout()
{
    // Load Wysiwyg on demand and Prepare layout
    if (Mage::getSingleton('cms/wysiwyg_config')->isEnabled() && ($block = $this->getLayout()->getBlock('head'))) {
        $block->setCanLoadTinyMce(true);
    }
    parent::_prepareLayout();
}


step-2Go to following path and open Form.php

app\code\local\Namespace\Modulename\Block\Adminhtml\Modulename\Edit\Tab\Form.php

and find function protected function_prepareForm() and add

$form = new Varien_Data_Form();
$this->setForm($form);
$form->setHtmlIdPrefix('yourmodulename');
$wysiwygConfig = Mage::getSingleton('cms/wysiwyg_config')->getConfig(array('tab_id' => 'form_section'));
$wysiwygConfig["files_browser_window_url"] = Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/cms_wysiwyg_images/index');
$wysiwygConfig["directives_url"] = Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/cms_wysiwyg/directive');
$wysiwygConfig["directives_url_quoted"] = Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/cms_wysiwyg/directive');
$wysiwygConfig["widget_window_url"] = Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/widget/index');
$wysiwygConfig["files_browser_window_width"] = (int) Mage::getConfig()->getNode('adminhtml/cms/browser/window_width');
$wysiwygConfig["files_browser_window_height"] = (int) Mage::getConfig()->getNode('adminhtml/cms/browser/window_height');

$plugins = $wysiwygConfig->getData("plugins");
$plugins[0]["options"]["url"] = Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/system_variable/wysiwygPlugin');
$plugins[0]["options"]["onclick"]["subject"] = "MagentovariablePlugin.loadChooser('".Mage::getSingleton('adminhtml/url')->getUrl('adminhtml/system_variable/wysiwygPlugin')."', '{{html_id}}');";
$plugins = $wysiwygConfig->setData("plugins",$plugins);


and add this code to display wysiwyg editor

$fieldset->addField('content', 'editor', array(
    'name' => 'content',
    'label' => Mage::helper('news')->__('Content'),
    'title' => Mage::helper('news')->__('Content'),
    'style' => 'width:700px; height:500px;',
    'wysiwyg' => true,
    'required' => true,
    'state' => 'html',
            'config' => $wysiwygConfig,
));

step-3

Go to following path and open yourmodulename.xml if its not available than create xml file

app\design\adminhtml\default\default\layout\yourmodulename.xml

and add


<?xml version="1.0"?>
<layout>
  <news_adminhtml_news_edit>
    <update handle="editor"/>
  </news_adminhtml_news_edit>
</layout>


Now reload your page really cool wysiwyg Editor Dispaly
Note: that this code was tested in Magento Version 1.6.1.0 and 1.7.1.0
Happy Editing!