set orthogonalEndSash(sash) {
        if (this._orthogonalEndSash === sash) {
            return;
        }
        this.orthogonalEndDragHandleDisposables.clear();
        this.orthogonalEndSashDisposables.clear();
        if (sash) {
            const onChange = (state) => {
                this.orthogonalEndDragHandleDisposables.clear();
                if (state !== 0 /* SashState.Disabled */) {
                    this._orthogonalEndDragHandle = append(this.el, $('.orthogonal-drag-handle.end'));
                    this.orthogonalEndDragHandleDisposables.add(toDisposable(() => this._orthogonalEndDragHandle.remove()));
                    this.orthogonalEndDragHandleDisposables.add(new DomEmitter(this._orthogonalEndDragHandle, 'mouseenter')).event(() => Sash.onMouseEnter(sash), undefined, this.orthogonalEndDragHandleDisposables);
                    this.orthogonalEndDragHandleDisposables.add(new DomEmitter(this._orthogonalEndDragHandle, 'mouseleave')).event(() => Sash.onMouseLeave(sash), undefined, this.orthogonalEndDragHandleDisposables);
                }
            };
            this.orthogonalEndSashDisposables.add(sash.onDidEnablementChange.event(onChange, this));
            onChange(sash.state);
        }
        this._orthogonalEndSash = sash;
    }
A reference to another sash, perpendicular to this one, which
aligns at the end of this one. A corner sash will be created
automatically at that location.

The end of a horizontal sash is its right-most position.
The end of a vertical sash is its bottom-most position.