Do you think it would make sense that the Select button (https://docs.mendix.com/refguide/select-button) has the same behaviour as for instance an Edit button when nothing is selected which results in a popup message "No selection available".
In the current behaviour, when nothing is selected, the page just closes and the application returns to the page of the reference selector.
What I would like to suggest is the possibility to be able to set a "minimum number of rows to select" (with a default of 0).