Also fix a bit of "Since:" annotations, some minor spacing fixing and
remove one useless test (if we test if a type is an item, we don't need
to test the children drawable type).
This reverts commit 246f9d284f.
This only reverts the part modifying libgimp* headers. All the part
switching to #pragma once in app/ was kept. See #14668.
I am using the same GimpDrawableChooser with an additional drawable_type
argument to only show the appropriate tab if we want to limit what can be
chosen.
None of our plug-ins actually use a GimpLayer or GimpChannel only arg so far,
but if we have some day, or if some third-party plug-ins want to have such arg,
now they quite easily can!
Similarly to the various GimpResource select PDB calls, this allows to call a
core dialog in order to choose a drawable which will be returned back to the
calling plug-in.
This new GimpPickableSelect dialog is a subclass of GimpPdbDialog and uses the
same GimpPickableChooser widget as GimpPickablePopup, except that since it's
inter-process window management, it is harder to make a popup positioned
accurately relatively to a parent (especially on Wayland). This is why it's a
separate widget as a simpler dialog (which we will still try to make transient
as much as possible across platforms).
