Download by git
git clone firstname.lastname@example.org:baloo-widgets.git
This command will download the baloo widget into a folder "baloo-widgets" at the place where you typed it.
Then you need to create a new folder named "build-baloo-widgets" with the commande : mkdir build-baloo-widgets
Go inside the bolder "build-baloo-widgets" by typing : cd build-baloo-widgets
After that you need to launch cmake : cmake ../baloo-widgets
Then you need to compile : make -j5
NOTE : For me i needed to install baloo 5 devel for compiling baloo. You can do the same : zypper install baloo5-devel