where the input extension is disabled, or alternatively be configured
with the "--without-xinput2" option.
+*** Scrolling with mouse-wheel lags in GTK3 builds.
+
+We don't know why this happens, but one workaround is to build Emacs
+with a different toolkit. For example:
+
+ ./configure --without-toolkit-scroll-bars --with-x-toolkit=athena
+
+This produces a build which uses Athena toolkit, and disables toolkit
+scroll bars which could sometimes be slow.
+
* Runtime problems on character terminals
** The meta key does not work on xterm.