De Icaza is best known for setting up the Mono project in a bid to develop a clone of the .NET programming environment for Linux. He styled it as an attempt to draw Windows programmers over to Linux. There is no evidence to show that it has achieved this aim.
De Icaza, who also spent many man-hours developing Moonlight, a clone for Silverlight which Microsoft hoped in vain to make a Flash killer, claims the reason for the Linux desktop not gaining marketshare was because developers behind the toolkits used to build graphical applications for Linux did not ensure enough backwards compatibility between different versions of their APIs. (Moonlight has now been abandoned.)