Default Hello, quick question

Hello new here found a lot of information on how too but have a quick question, any one know which PNG files to change in order to customize the keypad on the pin unlock screen on the thrive found some I think is right but I don't want to screw this up I'm looking in framework-res.apk /Res/drawable-mdpi/sym_keyboard_num 1,2,3,4 etc and the OK button please let me know if I've got the right files?
Thanks in advance for your help

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