File Manager App may be brought to Ubuntu Touch stable, since it is part of the Ubuntu Touch Core Apps.
Among other new features and improvements, File Manager App got a Paste button, that pastes the files from the copy buffer (the files that have been selected and copied). It also has an item count feature, allowing the user to see how many files will be pasted.
In order to install File Manager App on Ubuntu 13.10 Saucy Salamander, Ubuntu 13.04 Raring Ringtail, Ubuntu 12.10 Quantal Quetzal and Ubuntu 12.04 Precise Pangolin, you need to install also the Ubuntu virtual machine (ubuntu-sdk). Do this for a successful installation:
$ sudo add-apt-repository ppa:canonical-qt5-edgers/qt5-proper
$ sudo add-apt-repository ppa:ubuntu-sdk-team/ppa
$ sudo add-apt-repository ppa:ubuntu-touch-coreapps-drivers/daily
$ sudo apt-get update
$ sudo apt-get install ubuntu-sdk ubuntu-filemanager-app