On Fedora with Gnome-shell 3, its been long time that I was not able to get transparent window. So, finally I thought to spend some time to try to fix that. Finally got that fixed with all the configurations below in the conkyrc. Here the default color is set to LightSkyBlue but feel free to change that.
I hope this helps fedora community who is struggling to get transparent window. And here is the code :
If you ever wondered what combination of some colors would look like but did not really feel like setting them in your xterm just to check them out. Or if you wanted to know about all the colors on you X window system then you can install this utility called xcolorsel.
You will need to setup the rpm-shere repo for this.
Using this tool is very intuitive, just select the color and then press set as foreground/background to check how the color combination would look.