Don't try to use drag-and-drop on browsers that don't support it

Author: marijnh

lib/codemirror.js

@@ -275,7 +275,7 @@ var CodeMirror = (function() {
       } else { lastClick = now; }
 
       var last = start, going;
-      if (!posLess(start, sel.from) && !posLess(sel.to, start)) {
+      if (dragAndDrop && !posLess(start, sel.from) && !posLess(sel.to, start)) {
         // Let the drag handler handle this.
         return;
       }
@@ -2009,6 +2009,15 @@ var CodeMirror = (function() {
     pre.innerHTML = " "; return !pre.innerHTML;
   })();
 
+  // Detect drag-and-drop
+  var dragAndDrop = (function() {
+    // IE8 has ondragstart and ondrop properties, but doesn't seem to
+    // actually support ondragstart the way it's supposed to work.
+    if (/MSIE [1-8]\b/.test(navigator.userAgent)) return false;
+    var div = document.createElement('div');
+    return "ondragstart" in div && "ondrop" in div;
+  })();
+
   var gecko = /gecko\/\d{7}/i.test(navigator.userAgent);
   var ie = /MSIE \d/.test(navigator.userAgent);
   var safari = /Apple Computer/.test(navigator.vendor);
@@ -2184,5 +2193,4 @@ var CodeMirror = (function() {
   CodeMirror.defineMIME("text/plain", "null");
 
   return CodeMirror;
-})()
-;
+})();