Wrong images deleted

I'd seen this before but couldn't determine the circumstance. I just installed the nightly build from 5/27 and installed 5 images. The wrong image program was used so I didn't get thumbnails, so I deleted them. When I went to delete the first one, using the trash can icon on the image, the dialog box appeared in the center of the page, over the second image. When I clicked "Yes" the Ajax (or whatever) animation appeared on the second image and that's the one that disappeared. When I used the enter key instead, the correct image disappeared.

It really seemed that when the mouse moves over an adjacent image for long enough for the original image to lose the focus, the most recently hovered-over is the one that gets deleted. Moving the dialog box around and hovering over different images before clicking "Yes" changes the result most of the time. This isn't 100% consistent, though.