The screen saver page was originally used to select which pictures should be displayed on the MD screen saver.
Now, this page has more functions and is really more of a photo manager (as of 1204). The page allows tagging and rotating images, mostly done trough the keyboard.
The keywords will be synced to the files by UpdateMedia, either manually or automatically if you have enabled that.
It is recommended to use the TAB key to move between fields.
Here is a list of the fields and their functions. Please note that all changes are instant(using AJAX), and there is no need to save the page anymore.
Displays the exif orientation of the image. Use <left key> and <right key> to rotate the image. Please note that the image is not actually rotated, rather the exif orientation tag is changed to make viewer rotate the image at display time.
Check this to select the image for the screen saver.
Displays any keyword tags attached to the image. Shift+Click on a keyword to remove it.
Used to add new keywords to the image. Typing in this field will open a lookup list with current keywords. If you type something that matches a item in the list, <return> will add the keyword to the image. If you want to add a new keyword and not use the one matched in the list, use Shift+Return. Use Shift+Up to copy all keywords from the previous image.
In the top of the screen saver page, there is a link to the Photo Browser.