Thanks for reaching out and sharing the feedback. To see the complete file name you can hover over the file and it will show the full name. Having said that, I agree, there is always a scope of improvement, so I will share your feedback with the Engineering team and you can do that too here: https://adobexd.uservoice.com/forums/353007-adobe-xd-feature-requests
Feel free to reach out if you have any other questions or feedback in the future.
It's not practical to force people to hover over file names just to be able to read them. It takes over a second for the tooltip to display and we shouldn't have to hunt around rolling over multiple files, repeating over and over, just to read the file name.