  In this paper, we study the structures of Schur algebra and Lusztig algebra
associated to partial flag varieties of affine type D. We show that there is a
subalgebra of Lusztig algebra and the quantum groups arising from this
subalgebras via stabilization procedures is a coideal subalgebra of quantum
group of affine $\mathfrak{sl}$ type. We construct monomial and canonical bases
of the idempotented quantum algebra and establish the positivity properties of
the canonical basis with respect to multiplication and the bilinear pairing.
