PCMan File Manager (PCManFM) is a file manager application developed by Hong Jen Yee from Taiwan which is meant to be a replacement for Nautilus, Dolphin and Thunar. Released under the GNU General Public License, PCManFM is free software. PCManFM is the standard file manager in LXDE, which is also developed by the same author in conjunction with other developers. Since 2010, PCManFM has undergone a complete rewrite from scratch. So the new PCManFM is totally different from the old 0.5.x series. Build instructions, the ways to setup, and configuration files are different, too.
Dissatisfied with GTK 3, Hong Jen Yee experimented with Qt in early 2013 and released the first version of a Qt-based PCManFM on 02013-03-26-0000March 26, 2013. He clarified, though, that this means no departure from GTK in LXDE, saying “The Gtk+ and Qt versions will coexist”.