private function _renderFileToTmpAndGetNewHref ($item, $minify = FALSE) {
		$path = $item->path;
		$tmpFileName = '/rendered_css_' . self::$systemConfigHash . '_' . trim(str_replace('/', '_', $path), "_");
		$srcFileFullPath = $this->getAppRoot() . $path;
		$tmpFileFullPath = $this->getTmpDir() . $tmpFileName;
		if (self::$fileRendering) {
			if (file_exists($srcFileFullPath)) {
				$srcFileModDate = filemtime($srcFileFullPath);
			} else {
				$srcFileModDate = 1;
			}
			if (file_exists($tmpFileFullPath)) {
				$tmpFileModDate = filemtime($tmpFileFullPath);
			} else {
				$tmpFileModDate = 0;
			}
			if ($srcFileModDate !== FALSE && $tmpFileModDate !== FALSE) {
				if ($srcFileModDate > $tmpFileModDate) {
					if ($item->render) {
						$fileContent = $this->_renderFile($srcFileFullPath);
					} else if ($minify) {
						$fileContent = file_get_contents($srcFileFullPath);
					}
					$fileContent = $this->_convertStylesheetPathsFromRelatives2TmpAbsolutes($fileContent, $path);
					if ($minify) $fileContent = $this->_minify($fileContent, $item->path);
					$this->saveFileContent($tmpFileFullPath, $fileContent);
					$this->log("Css file rendered ('$tmpFileFullPath').", 'debug');
				}
			}
		}
		$tmpPath = substr($tmpFileFullPath, strlen($this->getAppRoot()));
		return $tmpPath;
	}