barbaz wrote:Is there a way to update some but not all of the active hosts files? Preferably one by one.
Not really. uMatrix will update whatever is deemed obsolete, so all obsolete filter lists will be update upon clicking "Update now". If all filter lists are up to date and you purge the cache for a specific list, only this list will be updated.
barbaz wrote:I am also noticing that cannot right-click a blocked image > View image (in new tab / middle-click), nor is it possible to copy the blocked image's URL from the DOM. Seems it's because of µMatrix messing with the DOM nodes despite my attempts to completely disable placeholders.
You're right, not very convenient. I could do what I do for frames, i.e. provide a link to the original image inside the placeholder. I am currently just not giving as much time to uMatrix as I do to uBlock. A new issue should be opened for this.
barbaz wrote:Changing the DOM in this way also has the privacy side-effect detriment of the website being able to realizing that *something* is blocking the image
That's true as soon as the DOM is tampered with one way or another, even just merely blocking without further DOM manipulation. If this is a concern, solution of course is to disable scripting to prevent js survey code from finding out, or XHR to prevent results of js survey code from sending information back to the server.
It has been argued that uMatrix should do what RequestPolicy is (was) doing with image placeholders, i.e. replace them with a custom placeholder instead of leaving a blank slate, in order to provide a visual hint that an image was blocked -- so this is why it's implemented this way.