Gets or sets whether the last LayoutGroup's child should stretch to occupy the whole group. This is a dependency property.
true, if the last LayoutGroup's child should stretch to occupy the whole group; otherwise, false.
By default, when an end-user closes all a LayoutGroup's child panels, the last remaining panel stretches and occupies the entire group. If the LastChildFill property is set to false, the last remaining child will keep the size specified by the BaseLayoutItem.ItemHeight and BaseLayoutItem.ItemWidth properties.