use c, not blocking copying

index.html

@@ -285,15 +285,9 @@ function keyboard_entry(ev) {
   if (/N/.test(k)) {
     toggle_blank();
   }
-}
-function keyboard_control(ev) {
-  var kC=ev.keyCode;
-  var k=String.fromCharCode(ev.keyCode);
-  if (ev.ctrlKey) {
-    if (k=='C') {
-      document.getElementById("filter").value='';
-      filter(ev);
-    }
+  if (/C/.test(k)) {
+    document.getElementById("filter").value='';
+    filter(ev);
   }
 }
 
@@ -433,7 +427,6 @@ function set_cookie(name,value) {
    ";path=" + window.location.pathname + ";max-age="+ (60*60*2).toString() + ";";
 }
 document.onkeyup=keyboard_entry;
-document.onkeydown=keyboard_control;
 document.onscroll=scroll_save;
 var linkReg=/([^\[]*)\[([^\]]+)\]\(([^\)]+)\)(.*)/;
 var linkPlain=/(.*)(http[^\s]+)(.*)/;