DockMvvmSample bugs

[cirrusone]

Hi,

I've found a few issues with the DockMvvmSample which I think are bugs. Here are steps to recreate:

Bug 1:

1. Drag Tool2 to floating tool
2. Change to Pinned
3. Drag pinned grip to any outer dock target
4. Tool2 disappears

Bug 2:

1. Drag Tool2 to floating tool
2. Change to Pinned
3. Drag pinned grip to itself over the same pinned grip
4. Tool2 is now both pinned and displayed with Tool2 displayed twice.

Bug 3:

1. Drag Tool2 to centre document tab
2. Drag Tool2 out of document tab to floating tool
3. Change to Pinned
4. Drag pinned Tool2 outside it's current view
5. Tool2 now has 2 views with one blank that cannot be moved or closed.

Only changes to sample project are this....

...\Dock-master\samples\DockMvvmSample\ViewModels\DockFactory.cs

public override IRootDock CreateLayout()
{
    var document1 = new DocumentViewModel { Id = "Document1", Title = "Document1", CanClose = true, CanPin = true };
    var document2 = new DocumentViewModel { Id = "Document2", Title = "Document2", CanClose = true, CanPin = true };
    var document3 = new DocumentViewModel { Id = "Document3", Title = "Document3", CanClose = true, CanPin = true };
    var tool1 = new Tool1ViewModel { Id = "Tool1", Title = "Tool1", CanClose = true, CanPin = true };
    var tool2 = new Tool2ViewModel { Id = "Tool2", Title = "Tool2", CanClose = true, CanPin = true };
    var tool3 = new Tool3ViewModel { Id = "Tool3", Title = "Tool3", CanClose = true, CanPin = true };
    var tool4 = new Tool4ViewModel { Id = "Tool4", Title = "Tool4", CanClose = true, CanPin = true };
    var tool5 = new Tool5ViewModel { Id = "Tool5", Title = "Tool5", CanClose = true, CanPin = true };
    var tool6 = new Tool6ViewModel { Id = "Tool6", Title = "Tool6", CanClose = true, CanPin = true };
    var tool7 = new Tool7ViewModel { Id = "Tool7", Title = "Tool7", CanClose = true, CanPin = true };
    var tool8 = new Tool8ViewModel { Id = "Tool8", Title = "Tool8", CanClose = true, CanPin = true };
...
}