My unit is in the city it has one movement point left and when I click on an enemy who stands right by the city, the stack walks out and stops there without attacking. Having them being able to attack groups next to the city (either preserving their movement points or not) would help solving also another issue. That one by which in certain situations units outside a city become impossible to attack if there is no free tile (meaning non-city tile) next to them. Attacking units in such way from inside a city may or may not expend movement points, in order to limit the number of attacks that can be done in the same turn.