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UI Subsystem

Location: src/MovieMakerCore/UI/

Movie Maker 2012 is a DirectUI application: native Win32 controls are mostly absent; instead, markup-driven element trees (UIFILE resources) are animated by behavior classes, with the Windows Ribbon Framework providing the command surface.

Tree​

UI/
  Ribbon/                    # Windows Ribbon framework integration
  UIBehaviorClasses.cpp/.h   # 50+ behavior implementations across 37 classes
  SundanceBehaviors.cpp/.h   # app-specific behaviors
  LayoutBehaviors.cpp/.h     # layout behaviors
  EditingBehaviors.cpp/.h    # rich edit, options dialog, help
  SpecialBehaviors.cpp/.h    # specialized behaviors
  TimelineBehavior.cpp/.h    # timeline surface behavior
  TimelineDataSources.cpp/.h # timeline item data sources
  SliderUI.cpp/.h            # custom slider
  ProgressUI.cpp/.h          # progress surfaces
  Dialogs.cpp/.h             # dialog hosting
  SundanceNativeHwndHost     # hosts native HWNDs inside DirectUI
  SundanceClipboardChainWindow # clipboard-viewer chain window
  SundanceUIComponents       # shared UI components
  UXBrush.cpp/.h             # drawing brushes
  DuiInterfaces.h            # DirectUI interface shims
  Legacy/                    # legacy (dead) UI paths — shipped but unused
  SundanceResourceIds.h      # resource ID assignments

The Ribbon​

UI/Ribbon/ implements the ribbon application model on uiribbon.h:

  • 67 command handlers, one class per functional group, each implementing IUICommandHandler::Execute / UpdateProperty.
  • Full UpdateState / ComputeCommandEnabled pass — command enablement is computed centrally from app state (selection, playback, project dirty state) rather than scattered.
  • MRU site registry — the recent-projects list is a site registry persisted to the registry; its "Count" query failure path returns the Win32 error (hardening fix from the 2026-09 pass).
  • The ribbon markup is RT_UIFILE_RIBBON (resource 10000) shipped in MovieMakerLang.dll.

Ribbon SDK quirks are preserved/documented: the Win10 SDK removed several ribbon APIs and uiribbon.lib GUIDs had to be defined manually (Quirk #6 and SDK Compatibility); the Vista Basic workaround is Quirk #12.

Behavior classes​

Behaviors are the DirectUI idiom: a behavior attaches to an element (by class attribute in the UIFILE) and reacts to its events. The reconstruction carries 37 behavior classes with 50+ OnMessage implementations, covering:

  • selection & drag on the storyboard/timeline (TimelineBehavior, TimelineDataSources)
  • ribbon-adjacent widgets (SliderUI, ProgressUI)
  • editing surfaces (EditingBehaviors: rich edit, options dialog, help)
  • window choreography (LayoutBehaviors, SundanceNativeHwndHost)

DirectUI itself​

The DirectUI framework runtime is not part of this repo's engine — the original shipped uxcore.dll / uxctl.dll / DuiDirect.dll as separate components. The reconstruction provides:

  • src/UXCore/ — a reconstructed DirectUI core (Element, HWNDElement, containers, controls, parser — 14 files), consumed by MovieMakerCore's UI layer and by the engine layer targets (see UXCore).
  • src/uxctl/ — the UxControlsInitProcess / UxControlsCreateObject / UxControlsUninitProcess control-host entry points.
  • src/MovieMakerCore/External/ — inert stubs for the parts of the external DirectUI surface MovieMakerCore imports (DuiUtilStub, UIControlsStub, DragDropStub, PSAStub) so the engine links and runs even though the real externals are absent on modern Windows.

Command IDs​

Command IDs are non-contiguous in the original resource space — preserved faithfully (Quirk #10); see UI/SundanceResourceIds.h and Resources/ResourceIds.h.