Raise PropertyChanged notification when LayoutContent.IsFloating changes

[bdachev]

Hi Dirk, that's first of series of small and hopefully safe PRs that I plan to do for changes in our fork to synchronize with main.

In this one we raise PropertyChanged for IsFloating property of LayoutContent which is read-only and indirectly changed when layout element is made floating or docked back to main window.
In our project there are places where we have bindings to IsFloating and they don't work as expected due to notifications not being sent.

[Dirkster99]

Hi Boris,

I was not aware of the case that the IsFloating property is not always changed when the Documents state changes.

Thanks for your input as this should help close another of these gaps :-)

[bdachev]

Well if you check the code IsFloating property is read-only and value is calculated in getter so in most cases it will be fine. It is just bindings that won't sense its changes without these notifications. :)

[Dirkster99]

I see what you mean and added a tag to mark this as bindable. I guess I should add this to pretty much all properties in the LayoutContent class (for sure to those that implement the DependencyProperty backing store).