We are having the same problem. It seems that the Webcontrols project for some reason is removed(?) from the full source download.
You can however find an aged Webcontrol (1.0.2152.23511) Source version at: http://www.dotnetnuke.com/Default.aspx?tabid=874
The sad thing is that 3.2.2 ships with version 1.0.2158.30731 DotNetNuke.WebControls.dll, which effectively means that we are stuck in the middle:
No source available for the 1.0.2158.30731 version of DotNetNuke.WebControls.dll, and a not compiling available source version of 1.0.2152.23511 of the DotNetNuke.WebControls.dll.
Probably is the 3.2.2 release NOT consistent ....
If anybody could shed some light ???, they would be most welcome 
Best Regards, Swan B