I am a relative newbie to QGIS 1.8, have looked through the previous answers, but have found nothing that resolves my issue.
I have a number of datazones as polygons on a layer. One of the datazones contains two islands that I need to split. With the layer selected and visible, editing turned on, I choose Select Features by Polygon. I click on a point in the sea around the island, move my mouse to another point, click again, a line appears, repat this until I get to the point where I want to put the last dot and right click. What I understand should happen at this point is that a filled shape should appear, but it doesn't, although the islands become selected.
Is this a bug or am I missing something obvious? The same is true of all of the vector layers from other shapefiles.
Thanks a lot