I can't seem to drag a file to an existing .7z or .zip file. I'm using 4.15 beta. In WinRar and Winzip does this just fine. I hope this gets implemented soon, because I find it very useful.
Secondly, I can't seem to select multiple files in my archive by selecting with my mouse. Again, this works in WinRar with no problem.
Lastly, is it possible to select the default compression to be zip when selecting 'add to <file_name>.7z'.
Keep up the great work. This is a great free and open source program!