PreviewPane.xaml(.cs) takes the center preview (Row 1 Col 1): the 1920x1080
canvas (OverlayCanvas/SelectionOverlay/BrandFlashLayer/SocialBarElement),
the text pull-out drawer, and the live-controls row (TRAX / game / mic meters,
volume sliders, speaker toggles, socials button) inside the preserved
glow/background Border.
Code-behind moved into the control (drive by DataContext==MainViewModel):
preview drag/select/resize/hit-test (Preview_Mouse{Down,Move,Up},
EndPreviewDrag, HitHandle, HitElement), webcam context-menu handlers
(WebcamMenu_ChangeWebcam/SetBorderAnimation/StopBorderAnimation/
FindBorderShape/CreateBorderAnimation/AddDoubleAnimation/SetBorderColor/
HideInScene/Remove), social-bar glow (SocialBar_MouseLeftButtonDown,
SocialsButton_Mouse{Enter,Leave}, SocialGlowTick), audio controls
(VolumeSlider_*, GameVolumeSlider_*, MicSpeaker_*, GameSpeaker_*,
SetSliderValueFromClick, FindParent), and TraxButton_*.
Window keeps the left source/property/chat panel + thumbnail strip + overlay
host, and routes the selection overlay and preview hit-testing through the
control's public surface (_previewPane.UpdateSelectionOverlay(bool),
IsClickInsidePreview/Drawer, PreviewPane.IsDraggableElement). BackgroundMenu_*
stayed in the window because the left-panel source context menu uses them
(the preview's own desktop/refresh menu binds RefreshCaptureCommand instead).
Preserved the outer preview Border (background/glow/margin) that was initially
dropped in the cut — caught and restored before commit. Pruned now-unused usings
(System.Net.Http, Media.Effects, Media.Animation, Media.Imaging, Shapes,
Threading) from MainWindow.xaml.cs.
Zero behavior change; build 0 warnings; 246 pass, only the 2 known failures.
Docs: ViewModels/index.md Phase 2 tracker updated in the same commit.
