Description
Many WTK implementations of org.apache.pivot.collections.Sequence fire xxxRemoved() events, even if no items are actually removed.
The events will include an empty list of items that were 'removed', but it would be preferable to simply suppress the event.
All other WTK Sequence implementations that I checked already suppress such non-events.
Fixes required for the following classes
org.apache.pivot.wtk.Accordion.PanelSequence
org.apache.pivot.wtk.Form.Section
org.apache.pivot.wtk.Form.SectionSequence
org.apache.pivot.wtk.GridPane.Row
org.apache.pivot.wtk.GridPane.RowSequence
org.apache.pivot.wtk.Menu.Section
org.apache.pivot.wtk.Menu.SectionSequence
org.apache.pivot.wtk.MenuBar.ItemSequence
org.apache.pivot.wtk.TabPane.TabSequence
org.apache.pivot.wtk.Window.ActionMappingSequence
org.apache.pivot.wtk.Window.IconImageSequence