QClipboard can operate in Clipboard or Selection mode (X11)
Implement using Clipboard selection on X11 and update QClipboard so that it can operate in either Clipboard or Selection mode. This mode parameter is ignored on non-X11 platforms.
New Behaviour:
- Highlighted text is copied into Primary selection
- All other "copy" commands such as Ctrl+C, copy the Clipboard selection
- Middle button click pastes from the Primary selection
- Add other "paste" commands such as Ctrl+V, paste from the Clipboard selection
- All non-text related data sources (Such as images) use the Clipboard selection
NOTE: Implemented in qlineedit and qlinemultiedit widgets NOTE: The source code mixes tabs and spaces (Even on the same line) so it's tricky to keep the diff clean in some places