My desktop computer is :
CentOS release 6.9 (Final) - Fully patched and up-to-date running KDE desktop
Firefox ESR 52.7.3 (64-bit)
Editing a file opened from the file manager in the new editor (NOT the HTML Editor) allows me to type in text but copy/paste does nothing using any of the following methods:

CentOS release 6.9 (Final) - Fully patched and up-to-date running KDE desktop
Firefox ESR 52.7.3 (64-bit)
Editing a file opened from the file manager in the new editor (NOT the HTML Editor) allows me to type in text but copy/paste does nothing using any of the following methods:
- Mouse - highlight text and right click to open sub menu and copy, then move mouse cursor to new position and right click to open sub menu and paste.
- Use the Copy/Paste icons in Firefox itself
- Use the Kbd short-cut Ctrl+C and then Ctrl+V