How to use the WYSIWYG editor (TinyMCE) in custom Admin Magento Module

A rich text editor(TinyMCE) is an often requirement for Admin Module as it makes the content editing work much easier.
In order to enable TinyMCE editor in textarea field, You need to do the following two things:

1> Including TinyMCE in Head

Add the following function in your Adminhtml Edit Class (MagePsycho_Demomodule_Block_Adminhtml_Demomodule_Edit):

protected function _prepareLayout() {
	parent::_prepareLayout();
	if (Mage::getSingleton('cms/wysiwyg_config')->isEnabled()) {
		$this->getLayout()->getBlock('head')->setCanLoadTinyMce(true);
	}
}

2> Enabling in Form Field

Add the following content field in your Adminhtml Form class (MagePsycho_Demomodule_Block_Adminhtml_Demomodule_Edit_Tab_Form):

$fieldset->addField('content', 'editor', array(
	'name'      => 'content',
	'label'     => Mage::helper('demomodule')->__('Content'),
	'title'     => Mage::helper('demomodule')->__('Content'),
	'style'     => 'height:15em',
	'config'    => Mage::getSingleton('cms/wysiwyg_config')->getConfig(),
	'wysiwyg'   => true,
	'required'  => false,
));

Note: Field Type must be ‘editor’ and ‘wysiwyg’ must be true

3> That’s All.

Here is what it looks like when loaded:

Note that this code was tested in Magento Version 1.6.1.0
Happy Editing!