I'm finally getting around to looking at the SharePoint Framework again (working on it in my few spare cycles when I don't have client work). The documentation says "Replace the propertyPaneConfiguration method with the code below which adds the new property pane fields and maps them to their respective typed objects." I replaced the code as instructed and I get an error "Cannot find name IPropertyPaneConfiguration" and "Return type of public property getter from exported class has or is using private name IPropertyPaneConfiguration" on the line:
protected get propertyPaneConfiguration(): IPropertyPaneConfiguration {
Should that read
protected get propertyPaneSettings(): IPropertyPaneSettings {