StDrawingArea uses the member variable needs_repaint to keep track
of whether it needs repainting. The variable is set to TRUE correctly,
e.g. on allocation or style changes - alas, it is never set to FALSE,
resulting in the area being repainted continuously.
https://bugzilla.gnome.org/show_bug.cgi?id=632197
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);
priv->context = cairo_create (surface);
priv->in_repaint = TRUE;
+ priv->needs_repaint = FALSE;
g_signal_emit ((GObject*)area, st_drawing_area_signals[REPAINT], 0);