This creates a very confusing zero-width group

Pressing ctrl-z, my immediate reflex, destroys any changes since the last save, without any possible redo.
Right-clicking this weird triangle gives no result. Clicking gives no feedback.
After a bit of fiddling with it, I discover that dragging it turns into a window, like this

Because I dragged left, this apparently puts the entry group into a cursed empty mode, that cannot be closed or selected, unless one tries to drag it all the way right again
What should have happened:
* user should not be able to create a group unless selection actually covers dialogue entries
* dialogue entry group should display correctly, no matter the drag direction
* dialogue entry group should *definitely* not be created if no drag is happening