Version: (using KDE 4.1.1)
Installed from: Fedora RPMs
When using the "Add to Desktop" right-click option from within the K menu on ktuberling the background of the icon appearing on the desktop is not transparent... it is actually black.
I've just tried using current trunk and I've not be able to reproduce it. Does it happen only with ktuberling or even with other apps? Which plasma style are you using?
The reporter is right, the 128x128 pixel icon has a black background, it will be fixed when i get someone with graphics knowledge to fix it, hopefully *soon*
Will be fixed in next KDE release.