Article # 19, added by Geoworks, historical record
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Mysterious object links



Q:
I added a couple of entries to a menu and now the contents of the menu
don't appear when I click on it. I looked that the source code, but I just
can't see what's wrong. 

A:
Sometimes when you add items to a menu (or any other object tree) you
forget to change all the links. Here's a rough example: 

    @object class object1 = {
        GI_comp = @object2,
                  @object3;
    }
    @object class object2 = {
    }
    @object class object3 = {
    }

Now say I want to add an object4 and group it with object3:
    @object class object1 = {
        GI_comp = @object2,
                  @object3;
    }
    @object class object2 = {
    }
    @object class objectgroup = {
        GI_comp = @object3,
                  @object4;
    }
    @object class object3 = {
    }
    @object class object4 = {
    }

Now I'm sure you can see something was forgotten, as this is a simple
example. I forgot to change the GI_comp field in object1, so it's pointing
to the wrong object. It should be like this: 

    @object class object1 = {
        GI_comp = @object2,
                  @objectgroup;
    }

In a more complex object tree, spotting this error is difficult.