Using the attached sample application please try the following scenario which will illustrate the floating status of the LayoutAnchorable:

(a) Start the sample application

(b) Click the 'Check Pane Status' button to see that the status indicates that the LayoutAnchorable is not floating:

(c) Close the Pane Status MessageBox, float the LayoutAnchorable and click the 'Check Pane Status' button to see that the status indicates that the LayoutAnchorable is floating:

(d) Close the Pane Status MessageBox, click the 'Dock Pane' button to Dock the LayoutAnchorable as a Tabbed Document and click the 'Check Pane Status' button to see the reported floating status of the LayoutAnchorable which does not seem appropriate:

(e) Why is there a disparity in the physically not floating status of the LayoutAnchorable and the reported floating status of the same LayoutAnchorable?