Currently, if a Style for an Element is created, and its Style Dummy Editor is created, there is a Properties Option which allows it to be "BasedOn" another Style.

However, performing this action fails to apply.

See attached video.

Repro Steps:

1) Create a Studio Project featuring a MainPage.xaml

2) Introduce a Button Element into the root Grid of the Page.

3) Right-click on the Button, and from the 'Styles' context menu category, navigate to 'Button'-->'Create'. Name it 'MyButton_Base_Style', and save it in the GlobalResources.xaml.
This will apply the 'Base' Style to the Button, and open it in the Style inline Dummy Editor.

4) Whilst in the Style's Dummy Editor, make a clearly visible change to any Property (Changing the 'Background' colour is a great candidate).

5) Exit the Style's Dummy Editor by clicking on the 'Home' button in the upper-left of the Stage.
This will return the scope back to the MainPage.

6) Right-click on the Button on the Stage again, and from the 'Styles' context menu category, navigate to 'Button'-->'Create'. Name it 'MyButton_Derived_Style', and save it in the GlobalResources.xaml.
This will apply the 'Derived' Style to the Button, and open the Style in the Style inline Dummy Editor.

7) With the 'Derived' Style open in the Style Inline Dummy Editor, in its Properties Panel, identify the 'BasedOn' Property, and from its dropdown, apply the 'MyButton_Base_Style' Style.
Observe how no effect has taken place, and the 'Derived' Button Style has not succeeded in being 'BasedOn' the 'Core' Button Style.

8) Expand the arrow on the left of the 'BasedOn' Property to reveal its Resource Selector, then from the 'Name' Property, select 'MyButton_Base_Style'.
Observe how no effect has taken place, and the 'Derived' Button Style has not succeeded in being 'BasedOn' the 'Base' Button Style.
Observe how the 'MyButton_Derived_Style' is selectable from this list, even if this is the Style currently active.

Expected Results: Applying another Style as 'BasedOn' applies it to the currently-active Style whilst in the inline Style Editor.
Expected Results: The current Style cannot be selected as the 'BasedOn' Style, as to not create a circular dependency.