BWindow: Style fix, 80 char limit.
Convert coords of B_MOUSE_IDLE in _SanitizeMessage()

When BWindow receives a message in screen coordinates and the
message has a target view, as it does when the message comes from
App Server, convert the coordinates to view coordinates before
passing the message along.

Revert the portion of hrev46532 where BView converts screen
coordinates and converts them since that happens in
BWindow::_SanatizeMessage() now.