Drag & drop images into Preferences - slight issue

When using this dialog :

And drag & dropping images into it I am having to do twice more times than not. In that I see what image I want in the explorer/lister, I click & hold to drag, when I drop it over the dialog the file has not been picked up and I have to do the process again.

Addendum : playing around with it a bit more the issue seems to always happen when first navigating to a folder (with images)

I've never seen it fail.

One thing that might cause confusion is that there are two drop targets within that dialog:

  1. If you drop a file on the list of images, on the left, it adds the file to that list.

  2. If you drop a file on the preview, on the right, it replaces the selected item with that file.