loading/saving Floating window bug

[bobsmith0]

Inside DockLayoutAdapter, GetShowAction, the action should not return anything if the docktree is not visible. This must then be not added to the show action list.

if ((dockTree.IsFloating) && (!dockTree.IsVisible)){
					return null;
				}

Otherwise it will try and load a hidden floating window, and will raise exception when loading the layout.