bug#55970: 29.0.50; Emacs crashes when dragging the scroll bar with "--with-pgtk" and "--without-toolkit-scroll-bars" configure flags

[समीर सिंह Sameer Singh]

Non-toolkit scroll bars use different kinds of events compared to
toolkit scroll bars.  PGTK only implements the latter kind, so turning
toolkit scroll bars off should trigger this piece of configure.ac:

  elif test "${window_system}" != "x11" && "${window_system}" != "none"; then
    AC_MSG_ERROR(Non-toolkit scroll bars are not implemented for your system)
  fi

Perhaps Sameer's configure script is out of date and needs to be
regenerated.

I cloned a fresh copy and configured it with the same flags, but still there was no error,

even though my configure.ac has the same lines.

AH_TEMPLATE(USE_TOOLKIT_SCROLL_BARS,
   [Define to 1 if we should use toolkit scroll bars.])dnl
USE_TOOLKIT_SCROLL_BARS=no
if test "${with_toolkit_scroll_bars}" != "no"; then
  if test "${USE_X_TOOLKIT}" != "none"; then
    if test "${USE_X_TOOLKIT}" = "MOTIF"; then
      AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
      HAVE_XAW3D=no
      USE_TOOLKIT_SCROLL_BARS=yes
    elif test "${HAVE_XAW3D}" = "yes" || test "${USE_X_TOOLKIT}" = "LUCID"; then
      AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
      USE_TOOLKIT_SCROLL_BARS=yes
    fi
  elif test "${HAVE_GTK}" = "yes"; then
    AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
    USE_TOOLKIT_SCROLL_BARS=yes
  elif test "${HAVE_NS}" = "yes"; then
    AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
    USE_TOOLKIT_SCROLL_BARS=yes
  elif test "${HAVE_W32}" = "yes"; then
    AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
    USE_TOOLKIT_SCROLL_BARS=yes
  elif test "${HAVE_BE_APP}" = "yes"; then
    AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
    USE_TOOLKIT_SCROLL_BARS=yes
  fi
elif test "${window_system}" != "x11" && "${window_system}" != "none"; then
  AC_MSG_ERROR(Non-toolkit scroll bars are not implemented for your system)
fi

On Wed, Jun 15, 2022 at 8:59 AM Po Lu <luangruo@yahoo.com> wrote:

Eli Zaretskii <eliz@gnu.org> writes:

> OK, but please explain how come the code in pgtk_send_scroll_bar_event
> leaves the modifiers unset, and that is still OK, notwithstanding the
> code in keyboard.c that expects either up or down modifier for any
> mouse click event?  Isn't that a bug regardless?

The mouse click code that expects an up or down modifier is only used
for scroll bar events when USE_TOOLKIT_SCROLL_BARS isn't defined.  The
code actually used with toolkit scroll bars starts at line 6359 of
keyboard.c.