Placing this line in a file named
.kateconfig of the base Gallery2 directory will tell Kate to use the correct formatting. You will also need to go into the Settings > Editor > Open/Save window to tell Kate how deep to look for the folder config file.
Kate, as of this writing (version 2.5.5), displays mixed indention just fine, but does not handle converting mixed indention into the correct format. You will need to use File:Repair-indention.zip to update files before commit.
kate: space-indent on; indent-width 4; mixed-indent on; indent-mode normal; tab-width 8; word-wrap-column 100; word-wrap off;