 
 	override func sessionChanged() {
 		super.sessionChanged()
+		loadPreviewIfNecessary()
 	}
 
 	// MARK: - notification handlers

			emptyNavigations.remove(navigation)
			return
		}
		Log.info("did finish webView load")
		guard let _ = parsedDocument else { return }
		updatePreview()
	}

		html += "<\(descriptor) index=\"\(chunkNumber)\" type=\"\(chunk.chunkType)\">\n"
		if !chunk.isInline {
			html += "<sectionToolbar index=\"\(chunkNumber)\" type=\"\(chunk.chunkType)\"></sectionToolbar>\n"
			html += "<sectionContent index=\"\(chunkNumber)\">\n"
		}
		html += htmlFor(chunk: chunk, index: chunkNumber)
		if !chunk.isInline {
			html += "\n</sectionContent>\n"
		}
		html += "\n</\(descriptor)>\n"
		return html
	}
