I would like to bump this feature suggestion as well.
The browser window size is much more useful than screen resolution. I also came across the same thread from 2011: https://forum.matomo.org/t/screen-window-size/2887
…the link that user julienm posted doesn’t work, so I’m not sure if this issue is being tracked anymore. Is there a status update on whether this feature was included somewhere in the current Piwik?
Thanks