Well, I grew with some stuff from XFCe, and mousepad is an advanced fork of leafpad. The most missed feature is that it uses ~/.recently-used.xbel (like GIMP does) for storing a list of recently opened files. And it seems to cut that list to 10 files maximum. The mplayer based program that Puppy Quirky NOP uses (not running that currently, so I cannot tell you what "X wrapper program for mplayer" that Puppy derivat is using, but that one makes an infinite list that grows and grows and keeps each and every opened video file...

That "open recently" (I have no mousepad running right now so I try to remember the exact name of the menu entry) is very convenient and I have a ~/.recently-used.xbel on each and every Slax* version pointing to the most-used and wanted text or html files, some copy&paste texts included, and with LXDE I need to browse to the full path and filename every time again.
And I know that wikipedia only tells us on the XFCe page "it was originally developed to provide printing support, which Leafpad lacked at that time." and omits the "open recently" / support of / using ~/.recently-used.xbel feature.
EDIT
moved from 'Development' to 'Development ‹ Porteus Desktops ‹ Lxde'
as this request is LXDE specific.
fanthom