Drag and Drop Post Images Problem on Macs

I am working with a friend who uses a mac and macbook. I use a PC. We noticed that when I click on an image in the edit mode of a post that the lines and sizing boxes form around the image. I can also drag and crop the image to a new location. On her macs, when she clicks on an image, it turns the image gray she says, but she can’t drag and drop or re-size.

I don’t know about the functions of a mac so I couldn’t help her.

Anyone any ideas? Thanks for any help or advice in advance.

Mike