6 ms·

That usually happens if that media player or image viewer edits registry to associate file types

wongarsu 8y ago
The design is slightly evil in that any unauthorized change of the registry keys doesn't just fail but instead invalidates a hash and makes windows revert to the default.
- anonymfus 8y ago
  There is no API difference between registry changes made by nonsanboxed user installed and built-in windows executables.
  - Dylan16807 8y ago
    I don't know exactly how it's implemented, and feel free to tell us, but wongarsu is absolutely correct about the behavior. For a while, whenever I hit the button in firefox to change default browser, suddenly my default browser was edge. Not the old setting, not the attempted new setting. It was very clearly not designed with 'protection' in mind.
    - Already__Taken 8y ago
      There's a hash of the registry key stored "securely" somewhere. Only the API the control panel default apps UI uses changes this registry key and updates the hash. When the application key is called to run and doesn't match the hash it's reset to the value from "C:\Windows\System32\OEMDefaultAssociations.xml" It's terrible behavior.
      - exikyut 8y ago
        What sorts of locks/permissions does this file have? Maybe you could make a tool that lets you make changes, schedules a modification of this file on next restart, and after the restart it propagates the changes in the registry too. Yes, "please reboot to apply your new mouse position^W^W^Wfile association changes", yay, but that'd work. Although I'd definitely hate it.
        deleted 8y ago
        [deleted]
      - anticensor 8y ago
        Does direct editing via regedit work as expected or does it also reset?
        Already__Taken 8y ago
        It will trigger a reset because you haven't updated the hash...
andrewshadura 8y ago
Which is bizarre if you consider that the original purpose of the registry (which appeared in Windows 3.1, I believe) was only to store file associations.

The design is slightly evil in that any unauthorized change of the registry keys doesn't just fail but instead invalidates a hash and makes windows revert to the default.

anonymfus 8y ago
There is no API difference between registry changes made by nonsanboxed user installed and built-in windows executables.
- Dylan16807 8y ago
  I don't know exactly how it's implemented, and feel free to tell us, but wongarsu is absolutely correct about the behavior. For a while, whenever I hit the button in firefox to change default browser, suddenly my default browser was edge. Not the old setting, not the attempted new setting. It was very clearly not designed with 'protection' in mind.
  - Already__Taken 8y ago
    There's a hash of the registry key stored "securely" somewhere. Only the API the control panel default apps UI uses changes this registry key and updates the hash. When the application key is called to run and doesn't match the hash it's reset to the value from "C:\Windows\System32\OEMDefaultAssociations.xml" It's terrible behavior.
    - exikyut 8y ago
      What sorts of locks/permissions does this file have? Maybe you could make a tool that lets you make changes, schedules a modification of this file on next restart, and after the restart it propagates the changes in the registry too. Yes, "please reboot to apply your new mouse position^W^W^Wfile association changes", yay, but that'd work. Although I'd definitely hate it.
      - deleted 8y ago
        [deleted]
    - anticensor 8y ago
      Does direct editing via regedit work as expected or does it also reset?
      - Already__Taken 8y ago
        It will trigger a reset because you haven't updated the hash...

andrewshadura 8y ago

Which is bizarre if you consider that the original purpose of the registry (which appeared in Windows 3.1, I believe) was only to store file associations.