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[STR Pending]

Link: https://www.fltk.org/str.php?L3521
Version: 1.4-feature


Here is the outcome of 3 further tests.

1) with Ubuntu in VirtualBox under MacOS
I used xev to see what X events occur.
- moving the mouse wheel up and down produces 
ButtonPress/ButtonRelease pairs for buttons 4 and 5, respectively.
- pressing shift and moving the mouse wheel:
xev sees no X event whatsoever (besides KeyPress when shift is pressed)

2) remote logging to a Debian system with X display to a local macOS
using XQuartz, an X server.
I used xev to see what X events occur.
- moving the mouse wheel up and down produces 
ButtonPress/ButtonRelease pairs for buttons 4 and 5, respectively.
- pressing shift and moving the mouse wheel produces
ButtonPress/ButtonRelease pairs for buttons 6 and 7, respectively.

3) same remote logging to a Debian system with local X display
and running the **unmodified** test/scroll FLTK program:
- moving the mouse wheel scrolls vertically
- pressing shift and moving the mouse wheel scrolls horizontally

I conclude that the change in function fl_handle() of src/Fl_x.cxx
proposed in comment #16 above may be the solution for
the X11 FLTK platform. But testing it on a genuine Linux system
without VirtualBox in between is necessary.


Link: https://www.fltk.org/str.php?L3521
Version: 1.4-feature