`gimp_unit_store_get_value()` clashes with the `get_value()` method of
its parent class GtkTreeStore. This means trouble for bindings, as seen
here in some pseudocode:
```vala
var unit_store = new Gimp.UnitStore();
// Which function are we referencing here, the one from GtkTreeStore or
// the one from GimpUnitStore? Worse, they both have different arguments
unit_store.get_value( ... )
```
Especially need to watch out with forgetting `(array)` and `(out)`
annotations, as they can really give a different API in certain (if not
most) bindings.
GtkHBox is a deprecated version of GtkBox, which we don't even use
anymore. It confuses the gtk-doc a build though, so let's fix it to get
rid of another warning.
When using GIR-based bindings that will eventually include the header
files (like Vala), we need to make sure to tell the gir-scanner what
file that is. Otherwise tools like `vapigen` have to make an educated
guess (which will be wrong).
If we don't do this, the clipboard owner doesn't get unreffed (also the
GtkClipboardClearFunc is not called either, but we don't set any so this
was not a big problem).
The main consequence was that copying was setting the Gimp object as an
owner, which kept a reference and prevent its finalize() method to run,
hence was leaking data (and in particular some GEGL buffers for
clipboard operations, which was how the issue became more visible upon
exit).
GObject introspection has issues handling random vfuncs (i.e. not part
of a GObject). Most of all, it needs to be able to give these a name
(so they can be used to cast in some higher level languages for
example). As such, give each vfunc in `GimpProgressVtable` a separate
typedef.
Properly initialize GimpSelectionTool::saved_operation upon
modifer-key press, even when some modifiers are masked out by
GimpPolygonSelectTool while the tool is active. This avoids
erroneously "restoring" the operation to a previously-saved state
once the modifier keys are released.
Add visual tab to spyrogimp plugin for a more intuitive, visual
way of specifying the spyrograph pattern.
In addition, fix using the selection as the fixed gear, and add
option to save the pattern to a path.
The GIR parser is giving warnings because both e.g. a signal, a
corresponding vfunc and a method emitting it are named
"channel_changed", which can and will give issues in some bindings.
The easiest option is to follow the general convention of starting the
signal emitters with `emit_`, which also makes clear the intention of
the method.