Linux Mint 15 provides three different style login displays, with the newest being HTML. Currently if you want to set your own background image you have to select Gtk, then pick an image, but it just doesn’t look pretty. The better way is to make an HTML theme and the instructions here provide a quick and easy way of doing just that.
The HTML themes are stored in /usr/share/mdm/html-themes/ directory. This is a protected system directory that can only be written to by root, but we don’t have to worry about that right now.
Linux Mint 15 comes with quite a few different style HTML login screens. We’re going to copy one we like, change the background image, compress it to an archive, and install it through Settings.
Copy the theme that you want to replace the background of to a new or empty directory within your home directory. Right-click the theme directory, then Copy To, and finally Home Folder. Then go to your home folder and rename the theme directory you just copied.
Copy Background Image
Copy the background image you want to use to the directory you copied the theme to. Keep in mind that the background should be large since it’ll cover the entire background of the screen.
Delete the screenshot.jpg file and the original background image. Make a copy of the new background image and rename it screenshot.jpg. This is the screenshot that’s shown when you select a login theme to use. So now you should have two copies of your background image, one named screenshot.jpg.
Edit The Theme
Now we just need to make a couple quick edits. We need to change the background image in the style file and we also need to pick a new name for the theme.
- Open the theme.css file with a text editor and change the theme image filename with the new one as shown in the screenshot above. Then save it and close the editor.
- Open the theme.info file with a text editor and change the theme name and description as show in the screenshot above. Then save it and close the editor.
Package It Up
Next we’ll create an archive of the entire directory so we can install it through the Login settings. Exit the directory, then right-click it and click Compress. Name how you’d like.
Add The Theme
Open up the System Settings panel and click the Login Screen. On the HTML selection, click the Add button and then browse to the archive
Select The Theme
Browse the list of themes to find yours and then select it by checking on the left side of the image. The circle to the left of the image should be filled in (unlike the screenshot above).
Try It Out
Close your windows and logout. You should now see your great new HTML login screen.