Login Theme being changed

Hi Ferry,

I will first start with that elementary-tweaks doesn't support freya sins the original developer has left the project.
So i wouldn't recommend to use it.

The 2 calculators is because between releases an calculator designed and made for elementary os by elementary developers has been pushed out for users to use( it came with an update). sins we don't have the power to control your computer we can't remove software from your computer.

you can choose which one you like best. if you want to remove the new one, this can be done by:
           "sudo apt-get remove pantheon-calculator"
if you want to keep the new one and remove the old one, this can be done by:
            "sudo apt-get remove gnome-calculator"

I don't know what would temper with the theming. sins the other 2 packages you name don't do it by them self. It is possible you installed something with synaptic and gdebi that tempers with it.
What i do is i reinstall the elementary desktop with this command:
          "sudo apt-get install --reinstall elementary-desktop"
or if you know for sure it is the theme you could try:
          "sudo apt-get install --reinstall elementary-theme"

Please NOTE this will remove any theming or changes you did with elementary-tweaks and other.

I hope that this will answer or solve your problems and questions.
Thanks for using elementary OS :)

Kind regards,
Kay van der Zander