https://bugs.gentoo.org/855011

diff -ruN a/src/Scrollbar.c b/src/Scrollbar.c
--- a/src/Scrollbar.c
+++ b/src/Scrollbar.c
@@ -1364,12 +1364,6 @@
       INFMESSAGE(returning due to LookAhead) ENDMESSAGE(NotifyThumb)
       return;
    }
-    /*
-       thumbProc is not pretty, but is necessary for backwards
-       compatibility on those architectures for which it work{s,ed};
-       the intent is to pass a (truncated) float by value.
-    */
-   XtCallCallbacks (w, XtNthumbProc, *(XtPointer*)&TOP);
    XtCallCallbacks (w, XtNjumpProc, (XtPointer)&TOP);
    ENDMESSAGE(NotifyThumb)
 }