Bug 258016 [PropertiesView] NPE in org.eclipse.ui.views.properties.PropertySheetViewer
At line 720. If the selection is null this will result in an NPE. Here is the offending code snippet: 714: // get the new selection 715: TreeItem[] sel = new TreeItem[] { selection }; 716: if (sel.length == 0) { 717: setMessage(null); 718: setErrorMessage(null); 719: } else { 720: Object object = sel[0].getData(); // assume single selection It would be better replaced with the following (sorry, no patch, I'm not set up for editing the platform!): // get the new selection TreeItem sel = new TreeItem[] { selection; if (selection == null) { setMessage(null); setErrorMessage(null); } else { Object object = selection.getData(); // assume single selection if (object instanceof IPropertySheetEntry) { // get the entry for this item IPropertySheetEntry activeEntry = (IPropertySheetEntry) object; // display the description for the item setMessage(activeEntry.getDescription()); // activate a cell editor on the selection activateCellEditor(selection); } } In fact, I'm not at all sure why the selection was being wrapped in a single element array at all, I'm guessing a holdover from old code?
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
updateCategories();
		}
        List children = getChildren(node);
        
        Set set = new HashSet(childItems.length * 2 + 1);
        for (int i = 0; i < childItems.length; i++) {
            Object data = childItems[i].getData();
            if (data != null) {
                Object e = data;
                int ix = children.indexOf(e);
                if (ix < 0) { 
                    removeItem(childItems[i]);
                } else { 
                    set.add(e);
                }
            } else if (data == null) { 
                childItems[i].dispose();
            }
        }
        
        int oldCnt = -1;
        if (widget == tree) {
			oldCnt = tree.getItemCount();
		}
        
        int newSize = children.size();
        for (int i = 0; i < newSize; i++) {
            Object el = children.get(i);
            if (!set.contains(el)) {
				createItem(el, widget, i);