Code-review follow-ups to the ImGui inspector:
- Add public UiRoot.Pick(x,y) over the private HitTestTopDown (honors
Z-order + modal exclusivity); StudioWindow uses it instead of a manual
UiElement.HitTest with subtracted ScreenPosition.
- RenderStack : IDisposable — disposes the GL pieces it owns in one place;
StudioWindow OnClosing + Dispose both call _stack?.Dispose(), closing the
error-path leak (only UiHost was disposed on the Dispose-without-OnClosing
path).
- Drop the stale _dt field; OnRender passes its own dt to Tick + BeginFrame.
- Fix a stale PanelFbo comment.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Task 3 of the acdream UI Studio plan. The studio previously drew the
panel straight to the window; it now renders the panel into an off-screen
FBO (PanelFbo) and displays it in an ImGui Canvas pane alongside a Tree
pane (recursive element hierarchy, click-to-select) and a Properties pane
(EventId/type/rect/anchors/ZOrder/flags of the selected element).
Click-to-inspect: a left-click inside the Canvas calls UiElement.HitTest
on the panel root (same-assembly internal access) and selects the topmost
element at the cursor, wiring the canvas directly to the tree selection.
PanelFbo lifecycle mirrors PaperdollViewportRenderer (RGBA8 color +
Depth24Stencil8 renderbuffer, GLStateScope-sealed, lazy resize on size
change). V-flip in DrawCanvas (uv0=(0,1)/uv1=(1,0)) corrects GL's
bottom-left FBO origin to ImGui's top-left convention so click Y maps
directly to panel-local Y without inversion.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
