I'm wanting to try & make a change to a KDE Workspace widget - specifically the Task Manager widget. I've cloned the KDE Workspace repository & found the applicable source code, but I haven't figured out how to compile it yet. The documentation I've found so far has been for compiling the whole of KDE, which is a somewhat more major undertaking than I was hoping to do at this stage!

So, I guess I have two questions:

• What is the smallest unit of code I can compile that includes the Task Manager widget, that I can then slot into my existing KDE install? (I'm running Kubuntu 13.04 with the KDE 4.10 that comes with it)
• How do I compile that?

I'm reasonably familiar with C/C++ and make, but I haven't used cmake before.

First step would be installing the appropriate development packages - namely for Qt, kdelibs, and kdepimlibs at a minimum to begin.
Then you'll need to configure the entire KDE Workspace clone, and build the individual applet. It will probably depend on other libraries in kde-workspace - which it will automatically build. Make sure to note those down.

Once built, you need to install the libraries it depended on, as well as the applet itself.
For development purposes, most people setup a install prefix under their home directory, and set the appropriate environment variables to allow KDE to find that install prefix.