Best answer by sampathsris
If that is your question, unfortunately this is not possible with the layout modifying functions available for user. This is done for good technical reasons. For example there could be forms where some tabs are dynamically loaded depending on the existence of a particular module (E.g. in Inventory Part window, the Manufacturing MRO tab would only be loaded if the MRO module is installed). In that case, the tab order can become ambiguous if one lets the user change it.
However, the tab order can be very easily changed with a customization.