In an additional private discussion with Meindert, we have clarified that the problem he is targeting is clearing the filter on MultiSelect blur (which effectively closes the popup).

Currently, the filter value is preserved when blurring the component which is not correct behavior and will be covered by this item: Filter value is not cleared on blur when PersistFilterOnSelect is enabled.

Apart from that, based on the current design, the filter value should be preserved if the popup closes but the MultiSelect remains active (focused). For example, when the user presses Esc to close the popup but the focus is still in the input of the MultiSelect. This indicates that the user is not yet done with the component.

Regards,
Nadezhda Tacheva
Progress Telerik