Bug 17292 Inconsistent Undo behaviour for Cut/Copy/Paste in outline
Build 20020521 (freeze 1) 1) Open a java editor on some class 2) In the content outline, select a method and do Ctrl+X to cut 3) Notice in the menus, Edit->Undo and Refactor->Undo are disabled 4) Now select the type node in the content outline, and Ctrl+V to paste 5) Still, neither Undo action is enabled 6) Now click inside the editor area to give it focus. 7) Now "Edit->Undo" is possible. So, the problems are: 1) Undo is not consistent, it's available for Paste but not Cut. 2) Even when undo is possible, it only becomes enabled when the editor is activated.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaOutlinePage.java
public Object getParent(Object child) {
					if (child instanceof IJavaElement) {
						IJavaElement e= (IJavaElement) child;
						return e.getParent();
					}
					return null;
				}
				
				public boolean hasChildren(Object parent) {
					if (parent instanceof IParent) {
						IParent c= (IParent) parent;
						try {
							IJavaElement[] children= filter(c.getChildren());
							return (children != null && children.length > 0);
						} catch (JavaModelException x) {
							JavaPlugin.getDefault().logErrorStatus(JavaEditorMessages.getString("JavaOutlinePage.error.ChildrenProvider.hasChildren.message1"), x.getStatus()); 
						}
					}
					return false;
				}
				
				public boolean isDeleted(Object o) {
					return false;
				}
				
				public void dispose() {
					if (fListener != null) {
						JavaCore.removeElementChangedListener(fListener);
						fListener= null;
					}