readline - improve readline editing
A support package that tries to make editing with readline easier. At the
moment, it reacts to clicking shift-left mouse button by trying to move the
text cursor to this position. It does so by generating as many cursor-left or
cursor-right keypresses as required (this only works for programs that
correctly support wide characters).
To avoid too many false positives, this is only done when:
- - the tty is in ICANON state.
- - the text cursor is visible.
- - the primary screen is currently being displayed.
- - the mouse is on the same (multi-row-) line as the text cursor.
The normal selection mechanism isn't disabled, so quick successive
clicks might interfere with selection creation in harmless ways.