Support applying custom formatting of selected text in QTextEdit

Consider the following:

• A user application has a requirement that words rendered in red color in a QTextEdit should remain red when selected.

However, Qt does not support setting custom formats on (parts of) selected text, or text being selected. Qt uses default highlight colors from the palette, and applies this to the entire selection.

It would be nice if Qt supported setting custom formatting on selected text, to support the above requirement, for example.