Method onGetInputChainElement

src/app/ui/document_view.h:70–70

    bool onCloseView(Workspace* workspace, bool quitting) override;
    void onTabPopup(Workspace* workspace) override;
    InputChainElement* onGetInputChainElement() override { return this; }

    // DocumentObserver implementation
    void onGeneralUpdate(doc::DocumentEvent& ev) override;