If you set Link's Direction via 'Link->Dir = 0' or whatever, whilst Diagonal Movement is on, if Link is walking, his direction is no longer set.
Setting Link's Direction with Diagonal Movement on [704]
Hang on...
You mean you want Link to walk sideways or something? Because it seems that Link's direction is still D_UP whenever he fires a weapon, which is when it should actually matter.
Well no, he won't walk sideways if you do that in Z1 movement, it just looks rather unusual.
Just, if you do it with diagonal movement on, nothing happens at all.
Like npc->Step, Link->Dir is very much a low-level internal variable, and writing to it is largely undefined. I've added a warning to zscript.txt.
You might be able to get the same effect by simulating keypresses as appropriate to turn him around.