- Viewport is not passed and stored as a shared_ptr instead of raw reference. - ViewportController can now be injected with an undo stack (not a ctor param anymore, as a preparation for the move of the undo stack to an interactor) - Added (temp) flag to disable emscripten events registration in the WebAssemblyViewport (because legacy client code deals with them directly) - Added emscripten_clear_timeout in ~WebGLViewportsRegistry - Removed GenericToolbox::HoldingRef whose responsibility is better served with proper callback un-registration.