Log Message:
gimp: update to 2.10.18.

Overview of Changes from GIMP 2.10.16 to GIMP 2.10.18
=====================================================

Core:

  - In gimp:replace, when compositing the same content over itself,
    i.e., when the input and aux buffers share the same storage and
    same tile alignment, pass the input buffer directly as output,
    instead of doing actual processing. In particular, this happens
    when processing a pass-through group outside of its actual bounds.

User interface:

  - Add new Symbolic-High-Contrast and Symbolic-Inverted-High-Contrast
    themes, which are automatically-generated high-contrast variants
    of the (original) Symbolic theme.  The contrast factor is settable
    in the makefile, and is currently at 1.5 for both themes.

  - Rename tools/invert-svg to tools/svg-contrast, which now takes a
    contrast-factor argument, and adjusts the input SVG contrast,
    instead of just inverting it.  Note that we can still use the tool
    to invert icons, using a contrast of -1.

  - Allow horizontal scrollbars in all the Preferences dialog tree-
    views, so that they don't limit the minimal width of the dialog
    (in particular, the UI- and icon-theme tree-views may contain
    arbitrarily-long paths).

  - Draw a border around the color FG/BG color areas as a pair of
    black and white rectangles instead of letting GTK do this. This
    imporoves the legibility of borders, especially in dark themes.

Tools:

  - In GimpPaintTool, when not snapping brush outline to stroke, make
    sure to properly snap the cursor position to 15-degree angle
    multiples in line mode, not only when painting the line, but also
    during motion.

Plug-ins:

  - Add naive support for CMYK 8-bit PSD files

Updated translations:

  - Basque, Catalan, Danish, Polish, Spanish, Swedish, Ukrainian

Bug fixes:

  - #4643, #4634

Developers:

  - Ell, Massimo Valentini

Translators:

  - Alan Mortensen, Anders Jonsson, Asier Sarasua Garmendia, Daniel
    Korostil, Jordi Mas, Piotr Drąg, Rodrigo Lledó Milanca

Overview of Changes from GIMP 2.10.14 to GIMP 2.10.16
=====================================================

Core:

  - In gimp_gegl_apply_cached_operation(), use gint64 for storing the
    total and processed pixel counts used for reporting progress, to
    avoid overflowing when applying an operation to a large image.

  - In GimpFilterTool and gimp_drawable_apply_operation(), use
    gimp_drawable_filter_set_add_alpha() to add an alpha channel when
    applying an operation that specifies "needs-alpha" to a drawable
    that can have alpha.

  - In GimpFilterTool, move all the drawable-filter option setup to a
    new gimp_filter_tool_update_filter() function, and call it
    whenever the drawable-filter's options need to be updated. This
    avoids duplicating logic in various places.

  - Improve the efficiency of decoding RLE data when loading ABR
    brushes, by reading entire scanlines into a buffer all-at-once,
    instead of reading the stream byte-by-byte.

  - GIMP now optionally phones home to find out if there's a new
    version available and then tells the user if there is one
    indeed. It also keeps track of the installer revision and then
    warns if there's a newer installer available. This can be disabled
    in Preferences. In that case, users still have the option to
    manually check for an update via the About dialog. The feature can
    be disabled entirely with the '--disable-check-update' configure
    switch.

Tools:

  - New 3D Transform tool where you can set vanishing point, camera's
    focal length, and the move and rotate layer, selection, path, or
    image in 2.5 space. With the "Unified interaction" option enabled,
    all three interaction modes of the grid (camera, move, and rotate)
    are available simultaneously. In this mode, the inner and outer
    regions of the item are used for moving and rotation, respectively,
    and the vanishing point is controlled through through a handle.

  - Transform tools now respect the Clip option and update the canvas
    preview accordingly.

  - New "Composited preview" option allows respecting layer's blending
    mode and position in the layer stack rather than rendering it as
    an overlay on top of the overall layer stack. This simplifies
    creating complex layer compositions greatly. The option requires
    mipmaps to be used and thus is disabled by default. It also comes
    with an experimental "Synchronous preview" suboption to render the
    composited preview synchronously. This reduces the lag for
    painting the preview, but can harm responsiveness for bigger
    images, where rendering the preview is slow.

  - Add a new "Preview linked items" option to the transform-grid
    tools. When this option is enabled, together with composited
    previews, the transform preview includes all linked layers and
    channels when transforming a layer/channel. Paths are currently
    unsupported.

  - New widget called GimpPivotSelector, a 3x3 grid of toggle buttons,
    is now used for selecting a natural pivot position (e.g. for a
    transform) relative to an item: its center, its corners, and the
    midpoints of its edges. Currently used in Rotate and 3D Transform
    tools.

  - Add "Show all" support to the Bucket Fill tool in line-art mode

  - Color picker and sample points now support displaying vlaues in
    Yu'v' (CIE 1976 UCS) color space.

  - The Symmetry Painting dock now has an "Enable reflection" option
    that allows painting patterns resembling a kaleidoscope.

  - Transform clipping is temporarily disabled for layer groups. No
    preview other than 'Adjust' works anyway. This will be fixed later
    on.

  - Construct a box-filtered mipmap hierarchy for the original brush
    on-demand, and the closest mipmap is used as the resampling source
    for downscaled brushes, significantly improving the output
    quality.

  - Now that painting is done in a separate thread, the display update
    rate has a far smaller impact on it. Increase the GimpDisplay
    update rate, which handles image updates, to 60 FPS, and the
    GimpDrawTool update rate to 120 FPS. In particular, the latter
    change makes the brush outline motion much smoother.

  - In the Airbrush tool, increase the maximal stamp FPS from 15 to
    60, and change the corresponding maximal Rate value from 150 to
    100. This technically affects tool presets, but we'll live.

  - Add a new "Snap brush outline to stroke" toggle to the "Image
    Windows" preferences page. When enabled, the brush outline in
    paint tools snaps to the individual dabs while painting, which is
    how it worked before version 2.10.16. Disable the option by
    default.  This seems to be what most other programs are doing, and
    it does give paitning a smoother feel.

  - The Warp Transform tool now respects settings for painting tools:
    showing the brush outline, snapping to dabs, and showing the paint
    tool cursor.

UI:

  - Tools are now logically grouped in the toolbox by default. Users
    can customize the groups to their liking or disable this feature
    altogether in the Preferences dialog (Interface / Toolbox page).

  - New opt-out compact style for sliders with revamped interaction.
    The widget uses a narrower layout, and the different
    upper/lower-half behavior is gone. Instead, the behavior depends
    on the mouse button and modifier used:

    - left-click is used for absolute adjustment,
    - Shift + left-click + drag changes value in small increments,
    - Ctrl + left-click + drag changes value in large increments,
    - middle-click enables numeric input mode;
    - right-click enables numeric input mode and selects the value.

  - The "You can drop dockable dialogs here" message is gone from the
    toolbox for good. Instead, highlight dockable areas when a user
    starts dragging a dockable dialog, and intensify the highlight as
    the dialog goes over a dockable area.

  - Consolidate UI for merging down and anchoring layers:
    As they are both mutually exclusive and serve an almost identical
    purpose, the "Merge down" and "Anchor Layer" are given \ 
mutually
    exclusive visibility in menus, and the anchor button is replaced
    with a merge down button in the Layers dockable whenever there is
    no active floating selection. Modifier keys are available:

    - Shift: merge layer group
    - Ctrl: merge visible layers
    - Ctrl + Shift: merge visible layers from last used values

Plugins:

  - In plug_in_compat.pdb, when wrapping an op node inside a graph,
    set the op node as the graph node's underlying operation. This
    allows gimp_gegl_apply_operation() to perform certain
    optimizations.

  - The Spyrogimp plugin now features a Visual tab where the inner
    mechanics of a spirograph is abstracted away, and you operate on
    amount of petals etc. The plugin now also allows saving a pattern
    as a path rather than rendering it to a layer as a bitmap.

  - Improve the loading speed for PSD files, mostly by eliminating
    excessive copies.

Filters:

  - Don't disable gegl:color-to-alpha (which has "needs-alpha")
    when the drawable doesn't have an alpha channel, if one can be
    added.

  - Don't disable color-to-alpha for grayscale drawable, since the
    operation is applicable to grayscale images (in particular, it
    doesn't add color where there was none), and since GIMP no longer
    distinguishes between layers and channels according to the
    drawable format when updating the filters actions.

Windows:

  - Installer: unofficial languages, ghostscript 9.50.
  - Installer: skip .debug files when they don't exist.
  - Installer: properly remove old icons on 32-bit installs and
    per-user installs.

macOS:

  - Set required variables if it is running from Apple application
    bundle.
  - The macOS build now ships with the dashboard dock for displaying
    perfomance graphs.

Updated translations:

  - British English, Catalan, Danish, French, German, Hungarian,
    Icelandic, Italian, Japanese, Polish, Russian, Spanish, Swedish,
    Turkish, Ukrainian.

Bugfixes:

   - #4172, #4194, #4205, #4218, #2543, #4185, #4246, #2794, #4209,
     #4278, #4372, #4187, #4392, #2674, #4338, #2862, #4203, #4204,
     #4354, #1266, #4584, #4174, #4285, #4366, #1975, #4605

Developers:

  - Alex Samorukov, Cyril Richard, Elad Shahar, Ell, Elle Stone,
    Jehan, Jernej Simončič, lillolollo, Massimo Valentini, Michael
    Natterer, Pascal Terjan, woob.

Translators:

  - Alan Mortensen, Alexandre Prokoudine, Anders Jonsson, Balázs
    Meskó, Balázs Úr, Bruce Cowan, Daniel Korostil, Jordi Mas, Julien
    Hardelin, Marco Ciampa, Piotr Drąg, Rodrigo Lledó Milanca, Ryuta
    Fujii, Sabri Ünal, sicklylife, Sveinn í Felli, Tim Sabsch, Zander
    Brown.