Instantly fixed the mixed content issues with several websites I need to do my work. This truly should be an option in the browser itself without going to about.

Solved the problem

many https websites for example have images loaded from other sites that are not https that if this addon is enabled then they wont work.
so I would have to add them all to blacklist of this addon.

so can you add an option for blacklisting domains that this images are from so I can still see them ?(their number is not high but they are visible in many sites I use so I have to blacklist those sites .
but if you add this option then I don't have to blacklist any site ,just the domains that are not https at all but are used in many https websites I use.

btw this is a very good addon but why https-everywhere doesn't do this ?

I have tested with that addon and I still get blocks on some websites that are not configured correctly when their css is on http and even thought https-everywhere make the webpage go https, the css is not converted to https before being blocked by firefox.

again thanks for writing an addon that works really good and fixes one of the bugs that others didn't thought to fix.

EDIT: I am not a developer so sorry if I come off as too stupid.
you are saying it is impossible to change the addon to tell it not to upgrade all the resources before blocking them and cant tell firefox based on a list?(either white listed or blacklisted?) .
and httpseverywhere has low developer time?
they are upgrading their addon like almost every two week and have already gone to web-extension way,which I don't think was easy for them.

and by the way how do I access the source code of addon ?
firefox used to have a "addon source code shortcut" but they removed it.
I am not entirely sure how firefox works anymore. do they allow not open source addons? if they don't then why not showing the source to others?

The extension does what it says, fluently replacing HTTP images with HTTPS when available. Probably works with other content too :)