code/Debug/Model/Design.php
public function init(Mage_Core_Model_Layout $layout, Mage_Core_Model_Design_Package $designPackage)
    {
        $this->area = $designPackage->getArea();
        $this->packageName = $designPackage->getPackageName();
        $this->themeLayout = $designPackage->getTheme('layout');
        $this->themeLocale = $designPackage->getTheme('locale');
        $this->themeTemplate = $designPackage->getTheme('template');
        $this->themeSkin = $designPackage->getTheme('skin');

        $this->layoutHandles = $layout->getUpdate()->getHandles();
        $this->setLayoutUpdates($layout->getUpdate()->asArray());
    }
public function init(Mage_Core_Model_Layout $layout, Mage_Core_Model_Design_Package $designPackage)
    {
        $this->area = $designPackage->getArea();
        $this->packageName = $designPackage->getPackageName();
        $this->themeLayout = $designPackage->getTheme('layout');
        $this->themeLocale = $designPackage->getTheme('locale');
        $this->themeTemplate = $designPackage->getTheme('template');
        $this->themeSkin = $designPackage->getTheme('skin');

        $this->layoutHandles = $layout->getUpdate()->getHandles();
        $this->setLayoutUpdates($layout->getUpdate()->asArray());
    }
Captures layout information

@param Mage_Core_Model_Layout $layout
@param Mage_Core_Model_Design_Package $designPackage