quteasearch is a fully featured, beautiful looking, open source, multi-tabbed, multi-threaded and extensible (via Custom Actions), graphical search utility for Linux with support for searching inside the files.
It is written in pure C++, it is feature packed and open source. I originally built it for personal use but later I decided to release the code as open source.
Here are some screenshots (code is coming!)
If you are asking yourself whether those things are CSD, yes they are but you can turn them off easy via the "..." button at the left bottom corner (a context menu pops up and the option is in it).