used script:
    t = re.sub(r'new QString\(("[^"]*?")\)', r'###NEW(\1)', t)
    t = re.sub(r'QString\(("[^"]*?")\)(\s*\+\s*)', r'###ADD(\1)\2', t)
    t = re.sub(r'QString\(("[^"]*?")\)(\s*\.)', r'###ADD(\1)\2', t)
    t = re.sub(r'QString\(("[^"]*?")\)', r'\1', t)
    t = re.sub(r'###NEW\(("[^"]*?")\)', r'new QString(\1)', t)
    t = re.sub(r'###ADD\(("[^"]*?")\)', r'QString(\1)', t)

As recommended by
https://google.github.io/styleguide/cppguide.html#The__define_Guard

Provide doxygen comments.
Use seconds from the onset.
Internal data now struct, not class.

Disable ManhattanStyle, that fixes background colors of some widgets under (at least) Plasma desktop manager.