If there's a version mismatch between compiled version (header) and
installed shared libpng library, structs are not created and NULL is
returned.

instead of checking for event->button == 3, so context menus
work correctly on the Mac. Didn't change the image menu yet
because thet requires some more refactoring.

The Tile Glass plug-in is moved from Lens And Shadow to Artistic
where it really belongs.

The Apply Lens filter is moved from Light And Shadow to Distorts
group where it really belongs.

Applying the filter noise slur on a white image produces
black artifacts at the first rows. Seen in meetthegimp162.mp4.

because they use G_CONST_RETURN which is deprecated in glib master.

amends commit 48ec1589, related to
CVE-2010-4543

depending on toggle buttons instead of libgimpwidgets' "set_sensitive"
hack.

Apply modified patch from Brennan Shacklett that fixes some more
plug-ins.

because it's deprecated to do that and badly crashes in GTK+ 3.0.
Use the display's keymap instead.

instead of gdk_pixbuf_get_from_drawable(), which is gone in GTK+ 3.0.

They are passed as default values in almost all cases, and can simply
be set later if needed.