Thanks for the advice. I tried the nub dance but the problem still exist. I'll try to work out the nub more. Nub configurator didn't help either. When I use the nub as mouse movement, it always move to the last direction I press. For instance, if I press the nub to the left, the cursor keep moving to the left even after I release the nub. The nub is still usable when I use it as mouse buttons, but it's still annoying because I have to manually center the nub after doing mouse click to prevent dragging instead of clicking.
One thing I don't understand, the right nub doesn't work when I turn on the pandora. I have to select 'Reset nubs' in the nub configuration to make it works. If I restart the pandora or run some apps/emulator, the right nub can't be used again, so I have to select 'Reset nubs' again to make it working. It's so annoying. Is there a shortcut for doing 'Reset nubs'?
The d-pad is super excellent!!! It feels great when using it for playing fighting games.