[Bf-codereview] Frame node upgrade and general node editor tweaks (issue 6200062)

[lukas.toenne at googlemail.com]

Using a space area event handler is probably not a good way to update
the mouse cursor, so i came up with a different solution.

The are typeinfo now has an additional flag event_cursor, when set this
causes the cursor callback to be called on every mouse move, instead of
just once when entering the area. This avoids problems of overriding the
default screen cursor updates.

The problem with flickering cursor still persists. I've tracked it down
to GHOST level: using standard CURSOR_* types instead of custom BC_*
cursors seems to work nicely. Not sure what the reason is, it seems the
custom bitmap cursors shift their position slightly on mouse moves and
intermediately set the standard cursor or so ...

http://codereview.appspot.com/6200062/