Main toolbar functionality only applies when viewing content in Design view, so when user view HTML view, the main toolbar will be hidden and HTML toolbar will be displayed and vice versa. ToolBar will also be adjusted when user focuses on editor or text area in Split view.
The state of main toolbar will be persisted when it's hidden. So when main toolbar is compressed to 5px height to provide larger editing area in Design view, the state will be persisted when user switches back from HTML view to Design view.
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User cannot compress HTML toolbar to 5px height. |