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In addition to vinod let me pint out, that jdev automatically removes bindings from the pagedef whenever you remove a tag or component from the page using the view, the structure panel or the property inspector. Only removing a component Udolf the source view prevents this.
This is not a bug, it's a feature. It helps to keep the pagedef small and clean. Beleave me, if your pagedef gets massed up, you'll get errors you don't connect to wrong bindings.
So of you keep this in mind, it should not be a problem.
Timo
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