Altap Salamander Support Forums

It would be nice to be able to include folders when filtering a panel

I second that.
For me, filtering by directories is even more important than filtering filenames.
And according to the newly introduced documentation, it should be possible. Quoting your help file:

Limiting the Files and Directories to Display
You can hide some files and directories in the panel. It can make the work much easier because you can focus only on important files and directories (all others can be hidden)...