Bug 271956 [Forms] SharedHeaderFormEditor should check for null header
The SharedHeaderFormEditor should be coded to handle null header. A null header may happen in some cases: although it is hard for me to pinpoint the exact cases, I did encounter a NullPointerException resulting from the following method: public boolean isDirty() { return headerForm.isDirty() || super.isDirty(); } I believe a simple null check (defaulting to false) would solve this situation.
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/editor/SharedHeaderFormEditor.java
private HeaderForm headerForm;
	
	private boolean wasHeaderActive= true;
	private Listener activationListener= null;
	private static class HeaderForm extends ManagedForm {
		public HeaderForm(FormEditor editor, ScrolledForm form) {
			super(editor.getToolkit(), form);
			setContainer(editor);
			if (editor.getEditorInput() != null)
				setInput(editor.getEditorInput());
		}
		private FormEditor getEditor() {
			return (FormEditor) getContainer();
		}
		public void dirtyStateChanged() {
			getEditor().editorDirtyStateChanged();
		}
		public void staleStateChanged() {
			refresh();
		}
	}
	/**
	 * The default constructor.
	 */
	public SharedHeaderFormEditor() {
	}
	/**
	 * Overrides <code>super</code> to create a form in which to host the tab
	 * folder. This form will be responsible for creating a common form header. 
	 * Child pages should not have a header of their own.