How can I access the horizontal Toolbar (where the Play/Pause button is) in custom editor?

Hello,

I’m wondering how can I access the horizontal Toolbar, and particularly the #ToolbarZoneLeftAlign to add my own buttons and dropdown? Now that the toolbar is inside a PanelSettings (named Toolbar), I thought it would be more accessible than before.

I also found this control but don’t understand where I could add it, neither which parent should I retrieve…
Unity - Scripting API: EditorToolbarDropdown (unity3d.com)

Has anyone got an idea?

Thank you