FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
I've found a couple of errors in the method: javax.swing.tree.DefaultTreeCellRenderer.updateUI().

(1) There is a typo on one of the properties:

    if (!inited || (getOpenIcon() instanceof UIManager)) {

That should be:

    if (!inited || (getOpenIcon() instanceof UIResource)) {

(2) This part of the method causes incompatibilities between themes, because the border is not removed if the margins are null:

    Insets margins = DefaultLookup.getInsets(this, ui, "Tree.rendererMargins");
    if (margins != null) {
        setBorder(new EmptyBorder(margins.top, margins.left,
                margins.bottom, margins.right));
    }

E.g., the Nimbus L&F has the "Tree.rendererMargins" property, which sets the border. After switching to the Windows L&F, which does not have the property, the Nimbus border persists, upsetting the appearance of the tree. This code also doesn't honor any user-set border. Suggested fix (not tested):

    if (!inited || (getBorder() instanceof UIResource)) {
        Insets margins = DefaultLookup.getInsets(this, ui, "Tree.rendererMargins");
        if (margins != null) {
            setBorder(new javax.swing.plaf.BorderUIResource.EmptyBorderUIResource(margins));
        } else {
            setBorder(new javax.swing.plaf.BorderUIResource.EmptyBorderUIResource(0, 0, 0, 0));
        }
    }



REPRODUCIBILITY :
This bug can be reproduced always.