How would one program an item while while you were using it. Enemies passed right through you and you passed through enemies. But you couldn't pass through walls. All this in a Zelda like game?
So for example add in the code for the collision event with walls for the player following code:
x=xprevious;
y=yprevious;
This will prevent the player from moving into walls. For moving objects such as enemies a more complicated code is required but let's assume enemies don't move either, give them following code:
if (global.itemused==false)
{
x=xprevious;
y=yprevious:
}
This will make you bump into enemies as well if global.itemused is false. Whenever you want to activate the item, set global.itemused to 1.