In VerbGui.ash:

struct Doors {
  ... //Add the following lines to the end
  import static void   SetAnimation (bool animate_on,  int view_id,  int animation_speed,  int delay_after);
  import static void   AnimateDoor();
};

in VerbGui.asc:

struct VerbsData {
... //Add the following lines to the end
//Sets whether to animate the player before interacting with doors.
bool door_animate_on = false;
int door_view_id = 0;
int door_animation_speed = 4;
int door_delay_after = 0;
}

The following function needs to appear BEFORE static int Doors::AnyClickSpecial in VerbGui.asc:

static void Doors::AnimateDoor()
{
  if (verbsData.door_animate_on)
  {
    player.LockView(verbsData.door_view_id);
    player.Animate(player.Loop, verbsData.door_animation_speed);
    Wait(verbsData.door_delay_after);
    player.UnlockView();
  }
}

The following function should be added after the AnyClickSpecial function (or could be placed before, probably):

static void Doors::SetAnimation (bool animate_on,  int view_id,  int animation_speed,  int delay_after)
{
  verbsData.door_animate_on = animate_on;
  verbsData.door_view_id = view_id;
  verbsData.door_animation_speed = animation_speed;
  verbsData.door_delay_after = delay_after;
}

Finally, replace Doors::AnyClickSpecial (the entire function) with:

// ============================= Door functions ==========================================

/***********************************************************************
 * AnyClickSpecial(int door_id, int obj, int x, int y, CharacterDirection dir, int nr_room, int nr_x, int nr_y, CharacterDirection nr_dir, AudioClip *opensound, AudioClip *closesound, int key, int closevalue)
 * This function extends AnyClick with the following parameters:
 *
 *   opensound: custom sound to be played, when the door is being opend
 *   closesound: custom sound to be played, when the door is being closed
 *   key: the id of the inventory item, that can unlock the door, -1 masterkey, -2 if the door cannot be unlocked
 *   closevalue: default 0 (closed), but you can also set 2 (locked).
 ***********************************************************************/
static int Doors::AnyClickSpecial(int door_id, int obj, int x, int y, CharacterDirection dir, int nr_room, int nr_x, int nr_y, CharacterDirection nr_dir, AudioClip *opensound, AudioClip *closesound, int key, int closevalue) {
  // key = -1: masterkey - even locked doors will be opened
  // key = -2: door can't be unlocked (like rusted)
  AudioChannel *chan;
  int result=1;

  if (Verbs.UsedAction(eGA_Close)) {
    if (Doors.GetDoorState(door_id) == 0 || Doors.GetDoorState(door_id) == 2) Verbs.Unhandled(1);
    else if (Doors.GetDoorState(door_id) == 1 ) {
      if (Verbs.AnyClickMove(x, y, dir)) {
        Doors.AnimateDoor();
        if (closesound != null) chan = closesound.Play();
        // Play default sound
        else if (verbsData.closeDoorSound != null) chan = verbsData.closeDoorSound.Play();
        object[obj].Visible=false;
        Doors.SetDoorState(door_id, closevalue);
      }
    }
  }
  else if (Verbs.UsedAction(eGA_Open)) {
    if (Doors.GetDoorState(door_id) == 0 || (Doors.GetDoorState(door_id) == 2 && key == -1 ) ) {
      if (Verbs.AnyClickMove (x, y, dir))
      {
        Doors.AnimateDoor();
        if (opensound != null) chan = opensound.Play();
        // Play default sound
        else if (verbsData.openDoorSound != null) chan = verbsData.openDoorSound.Play();

        object[obj].Visible=true;
        Doors.SetDoorState(door_id, 1);
      }
    }
    else if (Doors.GetDoorState(door_id) == 1 ) Verbs.Unhandled(1);
    else if (Doors.GetDoorState(door_id) == 2 )
    {
        if (Verbs.AnyClickMove (x, y, dir))
        {
          Doors.AnimateDoor();
          if (!String.IsNullOrEmpty(verbsData.door_strings[eDoorStringLocked])) player.Say(verbsData.door_strings[eDoorStringLocked]);
        }
    }
  }
  else if (Verbs.UsedAction(eGA_WalkTo)) {
    if (Doors.GetDoorState(door_id) == 1) {
      if ( verbsData.exitDoorDoubleclick && DoubleClick.Event[eMouseLeft] )
      {
        if (Verbs.MovePlayerEx(player.x, player.y, eWalkableAreas) > 0 ) player.EnterRoom(nr_room, nr_x, nr_y, nr_dir);
        result = 2;
      }
      else
      {
        if (Verbs.GoTo(2)){
          player.EnterRoom(nr_room, nr_x, nr_y, nr_dir);
          result = 2;
        }

      }
    }
    else Verbs.AnyClickMove(x, y, dir);

  }
  else if (Verbs.UsedAction (eGA_LookAt) && !String.IsNullOrEmpty(verbsData.door_strings[eDoorStringLookAt]) ) {
    if (Verbs.AnyClickMove (x, y, dir)) player.Say(verbsData.door_strings[eDoorStringLookAt]);
  }
  else if (Verbs.UsedAction(eGA_UseInv) && key >= 0) {
    if (Verbs.AnyClickMove(x, y, dir)) {
      Doors.AnimateDoor();
      if (player.ActiveInventory == inventory[key] ) {
        if (Doors.GetDoorState(door_id) == 1 ) {
          if (!String.IsNullOrEmpty(verbsData.door_strings[eDoorStringCloseFirst]) ) player.Say(verbsData.door_strings[eDoorStringCloseFirst]);
        }
        else if (Doors.GetDoorState(door_id) == 2 ) {
          if (verbsData.unlockDoorSound != null) chan = verbsData.unlockDoorSound.Play();
          if (!String.IsNullOrEmpty(verbsData.door_strings[eDoorStringUnlock])) player.Say(verbsData.door_strings[eDoorStringUnlock]);
          Doors.SetDoorState(door_id, closevalue);
        }
        else if (Doors.GetDoorState(door_id) == 0 ) {
          object[obj].Visible=false;
          Doors.SetDoorState(door_id, 2);
          if (!String.IsNullOrEmpty(verbsData.door_strings[eDoorStringRelock])) player.Say(verbsData.door_strings[eDoorStringRelock]);
        }
      }
      else if (!String.IsNullOrEmpty(verbsData.door_strings[eDoorStringWrongItem])) player.Say(verbsData.door_strings[eDoorStringWrongItem]);
    }
  }
  else result=0;

  return result;
  // 0 = unhandled
  // 1 = handled
  // 2 = NewRoom
}