Every app module now reaches liboakengine exclusively through
oakengine_* C calls, EngineEventBridge subscriptions and app-side
handle headers (cliphandle/keyframehandle/nodevaluehandle/oakvaluehelper).
Direct C++ command construction, engine signal connect()s, and engine
type usage in MOC-visible signatures are gone: 557 -> 0 undefined
olive:: symbols in oak-editor.
- SequencePreset::Save() wrote element "interlacing_" while Load() read
"interlacing", losing the interlacing mode on preset round-trips;
Save() now writes "interlacing" and Load() accepts both for backward
compatibility with existing preset files
- ExportFormatComboBox: current_ was never initialized (UB on GetFormat
before first user selection)
- ExportSubtitlesTab::SetSidecarEnabled() called setEnabled instead of
setChecked, so restored export params could never re-enable sidecar
subtitles
- h264section.h: static const int constants were odr-use unsafe (link
error when referenced); changed to static constexpr