nullSelectionOnBlur is used for places where VE is one of multiple inputes, e.g. in Flow.
The surface is deactivated when the window opens, then re-activates as soon as a transaction happens (behaviour required for T221291), e.g a temporary annotation is applied by the link inspector, or a dummy comment inserted by the comment inspector.
In full document VE this isn't a problem because the surface is deactivated again when the focus is moved to the inspector, but when nullSelectionOnBlur is set, moving the selection to the inspector just clears the original document selection.
|Expected (VE)||Observed (Flow)|
Note the missing grey box around the inspected object, and the incorrect position of the triangle callout with respect to the comment icon.