FULL PRODUCT VERSION :
A DESCRIPTION OF THE PROBLEM :
JTabbedPane$Page presents one Accessible child, which is the Component on the tab.
The default implementation of Component.getAccessibleContext().getAccessibleIndexInParent() is to count the components using getParent(), but the accessible parent should be JTabbedPane$Page not the parent of the component which is a JTabbedPane.
Down the tree: JTabbedPane > JTabbedPane$Page > Component.
Up the tree: Component > JTabbedPane.
This results in an inconsistent index for the Component, as it will always be index 0 when going down the tree, but the index will be the tab index going back up the tree.
Component$AccessibleAWTComponent.getAccessibleIndexInParent() should use Component$AccessibleAWTComponent.this.accessibleParent to find the index of the component.
REPRODUCIBILITY :
This bug can be reproduced always.