Bug 36672 call hierarchy: Should show a progress bar
The Call Hierarchy view should show a progress bar when searching for callers/callees, allowing the user to abort the search.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/callhierarchy/CallHierarchyContentProvider.java
return new Object[] { dummyRoot.getRoot() };
        } else if (parentElement instanceof MethodWrapper) {
            MethodWrapper methodWrapper = ((MethodWrapper) parentElement);
            if (shouldStopTraversion(methodWrapper)) {
                return EMPTY_ARRAY;
            } else {
                return methodWrapper.getCalls();
            }
        }
        return EMPTY_ARRAY;
    }
    private boolean shouldStopTraversion(MethodWrapper methodWrapper) {
        return (methodWrapper.getLevel() > CallHierarchyUI.getDefault().getMaxCallDepth()) || methodWrapper.isRecursive();
    }
    /**
     * @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(java.lang.Object)
     */
    public Object[] getElements(Object inputElement) {
        return getChildren(inputElement);
    }
    /**
     * @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(java.lang.Object)
     */
    public Object getParent(Object element) {
        if (element instanceof MethodWrapper) {
            return ((MethodWrapper) element).getParent();
        }
        return null;
    }
    /**