How can I enable or disable the opening of local files into the viewer?
You can use the showLocalFilePicker option in the PDFTron.WebViewer constructor. If this option is set to true then a button will displayed in the top toolbar allowing users to pick a file from their computer and dragging and dropping of files from their computer will be enabled. If the option is set to false then the button will not be displayed and drag and drop will not be enabled. By default this option is set to false.