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Tweaking Reader View Extension (extension security issue)

  • I have long wanted to change the "sepia" colour in Reader View (Version 2) - the reader that is a porting of Firefox Reader View. The provided colour is far too bright. Details of how I did this are below.

    But it should not of worked! Any change to an extension (other than by updating it) should result in the change being detected and the extension being disabled.

    On my iMac, I could edit the extension, and my changes worked perfectly. But on my MacBookPro the proper behaviour occurred: the extension was disabled and I was given the option to "repair" it which resulted in my changes bing overwritten.

    I cannot see any difference in the setting settings for Opera on my devices (both running latest OSX and Opera).

    So my iMac has some "security hole" for Opera Extensions ... where is it???

    Note: the extension folder name is random (in my case gfaafookaidboehhnhojbebjpjbnnfg) but you can identify the correct one by the sub folder name which is the version (in this case 2_0) and by the contents therein.

    Replace the HTM color code #FFFAFD with #e7d9c3 or with any color code you like in the following two files.

    For color examples, see or

    content.js located in:

    /Users/{your user name}/Library/Application Support/com.operasoftware.Opera/Extensions/gfaafookaidboehhnhojbebjpjbnnfgl/2_0/js

    search for the phrase color === 'sepia’

    html += " } else if (color === 'sepia') {"
    html += " = '#e7d9c3';";

    aboutReaderControls.css located in:

    /Users/{your user name}/Library/Application Support/com.operasoftware.Opera/Extensions/gfaafookaidboehhnhojbebjpjbnnfgl/2_0/css

    search for the text “sepia-button”

    .sepia-button {
    color: black;
    background-color: #e7d9c3;