This will look especially odd when it's used e.g. with an editor which has some toolbar (inline or balloon) because that toolbar will disappear once the editor loses the focus.

cc @oleq @oskarwrobel
BlockToolbar should be always visible in Letters so it should be configurable.
Why should it be always visible in Letters?
Because in Letters it is inside UI element and there is no need to hide it on blur.
Would it be a big loss if it was hidden? If its state will be based on editor.ui.focusTracker#isFocused, then you could also control whether it disappears when the focus is moved to e.g. comments.
I got used to permanently visible BlockToolbar in Letters and probably it's difficult for me to see this from a different pov. @pjasiun @dkonopka WDYT?
Block toolbar in Letters hides if the selection is in the title and if you blur Letters when selection is in the title, so for me it is fine if it disappears whenever you blur the editor.

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Block toolbar in Letters hides if the selection is in the title and if you blur Letters when selection is in the title, so for me it is fine if it disappears whenever you blur the editor.