Question Show button inside the overlay?

Hello I'm developing a tool and I recently discovered the existence of overlays and how to use them well, I already have some things implemented but there are situations that I don't know if I didn't know how to implement them well or the UI builder-overlay system is still young.

Then I Will leave you the problems that I had and I would appreciate it if you could tell me why they happen.

1) Buttons in the Overlay are not highlighted when selected.

In the following images I show how the "All mode" button is highlighted in light blue when I select it in the "Preview mode" but having it in the overlay it is not highlighted automatically, I know that highlighting is the product of having "Focusable" activated " which is activated but still does not work.



What would be the correct way to use this so that it would be highlighted correctly or should I make my own implementation for this?

2) Buttons hide when docked it

Unlike the unity tools that when docked it they continue to show the buttons within them in the implementation that I have these buttons are hidden inside a small panel that must be displayed, this is still useful but it is a bit cumbersome after a time.

Here is an example of how it works with the unity tools:


Here is an example of how it works in my implementation:



What should I do to make my Overlay look like the unity tool?

3) How can I have the overlays always open?

Another query that I have is, I can see that the unity base overlays start open but the ones that I have created I have to open manually, this is a problem since when I passed the tool to a colleague, he did not know that the tools were hidden, and If I wanted to publish it to the public, it would be annoying if they did not understand how to use the tool because this overlay is hidden.