Thanks for your reply. Since I use some QPlainTextEdit's facilities such as QPlainTextEdit::setExtraSelections() to display some information, using a label is not an option for me.

I ended up writing a simple "key press eater" event filter to disable Ctrl+A and Ctrl+C.

I'm still curious as to whether allowing Ctrl+A and Ctrl+C even when setTextInteraction(Qt::NoTextInteraction) has been called is intentional or not.