Feature request: Use a different window class name (WM_CLASS) for selection

[UtkarshVerma]

Windows 10's snipping tool is really intuitive to use. When the tool is opened, it blurs the entire region and selecting a region unblurs the selected region.

When using a compositor like picom, I can easily specify regions to be blurred based on the WM_CLASS property. I'm not sure but I think this only requires changing this line in the source code:

https://github.com/naelstrof/slop/blob/ed94f0c802b7cd39850a1552e7b3d3db3e6b0ff9/src/xshaperectangle.cpp#L45