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Component c1 adds component c2, and binds the nextbutton.disabled to c2's property "disabled".
When the tree gets rendered createContent for c1 gets called first, and the binding also executes at that point, getting "disabled" from c2 component that is not yet built.
If c2 changes the state of disabled in createContent then c1 has seen the wrong value. This test checks that binding executes after ALL builds are complete.