X11: fix extraneous (undefined) event state bits

- Restrict FL_BUTTONS mask to only three valic mouse buttons.
  Pseudo mouse buttons 4-7 are used for FL_MOUSEWHEEL events and
  are no longer reflected in Fl::event_buttons().
- Return only state of mouse buttons 1-3 in Fl::event_buttons().
  Buttons 4-7 are not "sticky" (used for FL_MOUSEWHEEL).
- Keep undefined keyboard related bits in Fl::event_state() for
  backwards compatibility and transparency. These bits may be masked
  out in a later release.
- Document Fl::event_state() bits for X11 in src/Fl_x.cxx.

Note: this is a bug fix for X11 only, Wayland and other platforms are
not affected.

1 files changed, 4 insertions, 4 deletions

diff --git a/FL/Fl.H b/FL/Fl.H
index 8d86370f3..796843d75 100644
--- a/FL/Fl.H
+++ b/FL/Fl.H
@@ -1263,22 +1263,22 @@ public:
     caused an FL_RELEASE event, you can use Fl::event_button() instead.
     \return a bit mask value like { [FL_BUTTON1] | [FL_BUTTON2] | [FL_BUTTON3] }
   */
-  static int event_buttons() {return e_state&0x7f000000;}
+  static int event_buttons() {return e_state & FL_BUTTONS;}
   /**
     Returns non-zero if mouse button 1 is currently held down.
     For more details, see Fl::event_buttons().
   */
-  static int event_button1() {return e_state&FL_BUTTON1;}
+  static int event_button1() {return e_state & FL_BUTTON1;}
   /**
     Returns non-zero if button 2 is currently held down.
     For more details, see Fl::event_buttons().
   */
-  static int event_button2() {return e_state&FL_BUTTON2;}
+  static int event_button2() {return e_state & FL_BUTTON2;}
   /**
     Returns non-zero if button 3 is currently held down.
     For more details, see Fl::event_buttons().
   */
-  static int event_button3() {return e_state&FL_BUTTON3;}
+  static int event_button3() {return e_state & FL_BUTTON3;}
   /**   @} */
 
   /**