problem creating and editing features at extent edges Well, the envelope worked, but the error was something else which I overlooked. The layer itself I was trying to edit wasn't, in fact, in wgs 84. Snapping the lines to the full extent wasn't possible because of that.
problem creating and editing features at extent edges @MatthewSnape It doesn't execute, and the abs. xy window closes.
As for the other link, all other editing and snap functionality works just fine when it's not at the edges.