In info.magnolia.cms.gui.control.Save.getSaveNode(HierarchyManager hm, Content rootNode) is a check for the nodeCollectionName. The nodeCollectionName is a String which is initialized as StringUtils.EMPTY, but it is checked against null. If you want to save something directly in a page a org.apache.jackrabbit.name.MalformedPathException is thrown.

Could you please change the code snippet in getSaveNode(HierarchyManager hm, Content rootNode)

// get or create nodeCollection
Content nodeCollection = null;
if (this.getNodeCollectionName() != null) {

to something like

// get or create nodeCollection
Content nodeCollection = null;
if (this.getNodeCollectionName() != null && ! this.getNodeCollectionName().equals(StringUtils.EMPTY)) {

thanks

Ralf