Hello Barry,

please check your path in detail - if there is no fault, try a complete/absolute path e.g. moi.ui.createDialog( 'X:\MoI_V4 beta\ui\nodeeditor.v.0.99.2017.12.18/index.html', 'resizeable,defaultWidth:680,defaultHeight:420', moi.ui.mainWindow );

Hope it helps
Karsten