st: marginal effects for simultaneous changes in interacted variables

[David Quinn <dxquinnx@gmail.com>]

Hello,

I am estimating a logit model as such: Y=X1 + X2 + X1*X2 + X3.

X1 and X2 are binary predictors, and I have interacted them using
factor notation.  X3 is a
control variable.

I'd like to assess the discrete change/marginal effects in my
dependent variable when X1 and X2 simultaneously move from 0 to 1,
setting x3 asobserved.

I used the following margins command to calculate this change:

margins, dydx(X1) at(X2=(0 1))

But this is not giving me the change that I desire.  It's giving me
the following two changes: 1.) From X1=0, X2=0 to X1=1, X2=0; and 2.)