Blender Git Loki

Merge branch 'master' into asset-browser-poselib

Support custom context menu entries for UI-lists, e.g. for pose assets

Makes it possible to add custom entries to the context menu of UI List items, by doing the following:
`bpy.types.UI_MT_list_item_context_menu.prepend(some_draw_function)`/`append(...)`.

The given draw function must check if the list is of the correct type. For that
to work I made it possible to get the hovered UI List using `context.ui_list`
and the list-ID via `ui_list.list_id`.

Merge remote-tracking branch 'origin/master' into asset-browser-poselib

Pose Library: rename `apply_flipped` to `flipped`

Rename the operator property `apply_flipped` to simply `flipped`, as the
verb ("apply") is already in the operator name. This will make it possible
to add a `flipped` property to the select/deselect operators too, keeping
things consistent.

No functional changes.

Pose asset operators: Check the type of the asset in the operator poll

Check that the asset received from context actually is an action ID
asset.

Add button to refresh the asset list from the asset view template

Adds an operator to refresh the asset list and exposes that next to the
asset library selector above the template, when showing an external
library.

Remove asset testing panel for the asset view template

There's a proper panel with the asset viewer now, for the poses. This
testing one will just confuse people.

Fix possible use of released stack memory

We'd store references to temporary objects, e.g. see
`AssetListStorage::ensure_list_storage()`. Stupid mistake, store a copy
of the `AssetLibraryReference` struct now (cheap to copy).

Support "Release Confirm" mode for the pose blending operator

This will make it possible to click and drag on the poses in the
asset view template to do the blending. On mouse release, the blended
pose will be applied.
This isn't used yet, follow-up commits will enable it.

This also hides the cursor and enables continuous grabbing when dragging
with the "Release Confirm" enabled. To be evaluated; maybe it should
always do this while blending.

Also fixes mouse hover highlights not being updated when confirming or
cancelling the pose blending operator.

Allow setting operator properties for the custom drag & activate OPs

The asset view template now provides a way to set the operator
properties of its custom drag & activate operators. In Python they are
returned from `UILayout.template_asset_view()` as tuple.

Includes some cleanup to better manage the data of the custom operators.

Prevent preview loading from triggering continuous redraws

The preview rendering notifiers would be continuously sent, causing
continuous redraws. In the File Browser that also happens (and I don't
think it's intentionaly) although it causes refreshes there that don't
do much and there won't be redraws unless necessary. Correcting this may
cause issues, so better to do it separately.

Issue is that the previews were fetched using the BLI_task API, and a
timer was started to send notifiers continuously. But there was nothing
to check if the tasks were done, so that the timer could be stopped.

Fix File Browser double-click not working while in pose mode

The pose apply operator would be invoked when double-clicking a
directory in the File Browser, while in pose mode.
The operator's poll would succeed because since 29887bbb329d, the
File/Asset Browser would just create a `AssetHandle` from the active
file received from context, without ensuring that the file actually
represents an asset.

Pose Library: correct status text when blending poses

Pose Library: remember last-used blend factor

When the interactive blending operator finishes, store the chosen blend
factor in the RNA properties. This ensures that pressing F9 shows the
actual factor, which can then be readjusted.

Pose Library: cleanly stop blending when quitting Blender

When Blender quits while the pose blending operator is active, set the
correct state (`POSE_BLEND_CANCEL`) before exiting, so that cleanup done
correctly.

Asset Browser: monitor subprocess after opening new Blender

Monitor the new blender subprocess from the "Open Blend File" operator,
and reload the asset browser after the subprocess stops.

Asset Browser: add "Open Blend File" operator to Asset browser context menu

Add an "Open Blend File" operator to the Asset Browser context menu,
which starts a new blender process to open the blend file containing the
active asset.

Merge remote-tracking branch 'origin/master' into asset-browser-poselib

Pose Library: remove use of `BONE_UNKEYED` bone flag

This bone flag was removed in rBfd10c21f51243921e645939e3f6a569c19864d8e.

No functional changes.

Pose Library: prevent auto-keying on linked Action

Prevent auto-keying when the current Action is a linked datablock.