From http://www.jwz.org/xscreensaver/xscreensaver-5.20.tar.gz

[xscreensaver] / OSX / jwxyz.m

diff --git a/OSX/jwxyz.m b/OSX/jwxyz.m
index f9dc5b007b163376c6fd8303b50064cd2164d3bd..de78750a2080ab87ba1abbde4fe1eb9ca3f6ad67 100644 (file)
--- a/OSX/jwxyz.m
+++ b/OSX/jwxyz.m
@@ -3218,11 +3218,25 @@ XLookupString (XKeyEvent *e, char *buf, int size, KeySym *k_ret,
                XComposeStatus *xc)
 {
   KeySym ks = XKeycodeToKeysym (0, e->keycode, 0);
-  char c = (char) ks;    // could be smarter about modifiers here...
+  char c = 0;
+  // Do not put non-ASCII KeySyms like XK_Shift_L and XK_Page_Up in the string.
+  if ((unsigned int) ks <= 255)
+    c = (char) ks;
+
+  // Put control characters in the string.  Not meta.
+  if (e->state & ControlMask) {
+    if (c >= 'a' && c <= 'z')    // Upcase control.
+      c -= 'a'-'A';
+    if (c >= '@' && c <= '_')    // Shift to control page.
+      c -= '@';
+    if (c == ' ')               // C-SPC is NULL.
+      c = 0;
+  }
+
   if (k_ret) *k_ret = ks;
   if (size > 0) buf[0] = c;
   if (size > 1) buf[1] = 0;
-  return 0;
+  return (size > 0 ? 1 : 0);
 }