I needed a colorpicker in my own project so I revised the one Mitchell wrote to make it work in ST2.
Since Sencha 2 does not have an extensions forum. I thought here should be an appropriate place to post it in case anybody may find it helpful.
It is on at https://github.com/Codier/Sencha-Touch-2-Colorpicker
Thank you for your reply. I replaced the original code in Ext.form.ux.touch.ColorPickerField.js with the updated code from your post, but I'm still getting - Uncaught TypeError: Cannot call method 'getPageBox' of null