Share CanvasMode GL dispatch adapters

docs/modernization/roadmap.md

@@ -1267,6 +1267,10 @@ clear, and clear-color restore paths use the same helpers. `NodeCanvas` and
 `NodeStrokePreview` now share that retained UI GL dispatch bridge for
 active-texture, fallback texture unbind, viewport/scissor, clear-color,
 color-buffer clear, and capability query/apply adapter endpoints.
+Retained `CanvasMode` overlay, mask, transform, and canvas-tip pick paths now
+also use the same bridge for active-texture, capability query/apply, viewport,
+read-framebuffer query, and RGBA8 pixel readback adapter endpoints while their
+mode logic remains in the legacy UI implementation.
 Desktop HMD eye rendering now routes eye framebuffer viewport changes through
 the tested `pp_renderer_gl` viewport dispatch while platform VR SDK bridges
 remain isolated for later platform-shell extraction.
@@ -2549,7 +2553,11 @@ Results:
 - Retained Canvas, NodeCanvas, NodeStrokePreview, and HMD viewport/scissor/
   capability execution now compiles through the renderer GL backend dispatch
   adapters with `pp_legacy_paint_document`, `pp_panopainter_ui`, and
-  `panopainter_app`.
+  `panopainter_app`. CanvasMode overlay, mask, transform, and canvas-tip pick
+  paths now also consume the shared retained UI GL dispatch for active-texture,
+  capability query/apply, viewport, read-framebuffer query, and RGBA8 pixel
+  readback adapter endpoints, removing another local raw-GL adapter cluster
+  from `src/canvas_modes.cpp`.
 - Windows desktop OpenGL context creation now consumes a tested
   `windows_wgl_core_context_3_3_config()` catalog from `pp_renderer_gl`, moving
   the active WGL context/pixel-format attribute literals out of the platform