Do an 'Open from' > 'URL...' and paste in http://shagie.net/wp-content/uploads/2015/05/Untitled-Diagra... (an example diagram I made several years ago) - its a png itself and you can open that up as a png, but I also exported it with the drawing embedded.
So when you open that up in the app, you'll get the drawing - not the raster version.
Also consider that I created that png 7 years ago - other drawing document formats have been less stable over that timeframe. I'm quite impressed with it.
Do an 'Open from' > 'URL...' and paste in http://shagie.net/wp-content/uploads/2015/05/Untitled-Diagra... (an example diagram I made several years ago) - its a png itself and you can open that up as a png, but I also exported it with the drawing embedded.
So when you open that up in the app, you'll get the drawing - not the raster version.
Also consider that I created that png 7 years ago - other drawing document formats have been less stable over that timeframe. I'm quite impressed with it.