Is it possible to add a dialog to the exit itself? So, when player walks into exit (teleport tile), it will force player to read important messages before going to the next room.
This feature will add dialog box into "exits" window in the editor.
Showing dialog on old room describes action when player hits that tile. Showing it on new room describes the setting of new room/event.
For simplicity, I think showing dialog just like in the ending screen works on both ways as it depends on the narrative.