Code review comment for lp:~mc-return/compiz/compiz.merge-fix771448-desktop-wall-edge-flipping-broken

So what I'm thinking is that we can probably remove the mousepoll + edge update stuff and do something like this:

1. On grab, turn all edges on (eg, toggleEdges)
2. Listen for xdndEnter and xdndLeave events
3. When an edge action is triggered, if we don't have "pointer" edge flipping enabled then:
   a. If "edge flip move" is enabled check if:
      1. There has been a grabbed window and
      2. Its grabbed for moving
   b. If "edge flip dnd" is enabled check if:
      1. We currently have the xdndEnter event for an edge.

This might require some core changes too - to check if an edge was entered for a DnD event.