Potlatch 2/vector background layers
Potlatch 2 supports vector background layers. These enable you to load external vector data, and to bring it into the map manually, rather than unthinkingly bringing in all data as an automated import.
To load a layer, click "Vector file..." in the "Background" menu. Select the filetype and URL of the file at the bottom, and click 'Load'. Once the file has loaded, it will appear in the list. (If you get a security error, the site hosting the file may need to add a crossdomain.xml file.)
You can bring through data from the background layer to the main map by alt-clicking it. (If you are using a Linux system whose window manager intercepts alt-clicks, you can click while holding down Shift and Control instead.) Only data that has been brought through to the main map will be uploaded when you save.
Please note that, at present, connectivity is not preserved when you bring data through. You will need to manually recreate any junctions in the dataset.