Change the colour of the blocked frame to grey.

[skudo12]

Grey stripes is more appealing and easy to the eyes than red stripes. Just a minor suggestion.

[gorhill]

Other users have asked me to also have a different visuals, also different from what you suggest. There is a lot of subjectivity here about how it would look better/nicer. My rationale for choosing a visual which quite stands out is to make clear that there was a frame at a particular position of a particular size, as sometimes these frames are used in a invisible (transparent) way to do not-so-nice things to the users.

Given that what would be "better" depends on the user's subjective taste (I personally like the content of the replacement to stand out), I will try to think of a solution to let the user override the stock visuals with his own css (unsure if possible, I need to investigate, but that won't be on my priority list for now).

[skudo12]

I understand as it is based on the user. However I do hope you find a better alternative for red stripes. Maybe a white rectangle and a red border.

[gorhill]

Maybe a white rectangle and a red border.

I think user needs to at least be able to also see through. If ever a web page had an invisible frame (say a malicious extension or a server-side malware installed one to intercept all user clicks and mouse move etc.), you would want to see what that invisible frame covers.

[darsain]

Came here to file the same complaint. The red stripes are more obtrusive than ads themselves.

Leave the stripes, the presence of frame should be noticeable, but change the color to something that doesn't stab my eyes. Preferably also make it transparent.

[gorhill]

The code already supports setting the transparency, only missing part is the UI widget to control opacity in Settings. Will look into this today.

[gorhill]

Also, while at it, I am no designer. it would be nice if someone with better design skills could contribute some kind of tilable pattern to serve as placeholder for blocked frames -- keeping in mind the replacement has to serve security first (make sure the user is informed that there was a frame there and it has been blocked). The red stripes is just what I came up the 3rd day I started hacking this extension back in Sep 2013.