needs-update

Typically called (indirectly) by a snip within the buffer to force the buffer to be redrawn.

For wx:media-edit% objects, calling this method may force the recalculation of location information if a maximum width is set for the buffer, even if the buffer currently has delayed refreshing (see refresh-delayed?).

• (send a-wx:media-buffer needs-update snip localx localy w h) -> void
      snip : wx:snip% object
      localx : inexact real
      localy : inexact real
      w : inexact real
      h : inexact real

  The localx, localy, width, and height arguments specify the area that needs repainting in the coordinate system of snip.