Allow dragging out of a CodeMirror instance

Closes #163

Author: marijnh

lib/codemirror.js

@@ -28,7 +28,7 @@ var CodeMirror = (function() {
           '<div style="position: relative">' + // Moved around its parent to cover visible view
             '<div class="CodeMirror-gutter"><div class="CodeMirror-gutter-text"></div></div>' +
             // Provides positioning relative to (visible) text origin
-            '<div class="CodeMirror-lines"><div style="position: relative">' +
+            '<div class="CodeMirror-lines"><div style="position: relative" draggable="true">' +
               '<pre class="CodeMirror-cursor">&#160;</pre>' + // Absolutely positioned blinky cursor
               '<div></div>' + // This DIV contains the actual code
             '</div></div></div></div></div>';
@@ -80,6 +80,7 @@ var CodeMirror = (function() {
 
     // Register our event handlers.
     connect(scroller, "mousedown", operation(onMouseDown));
+    connect(lineSpace, "dragstart", onDragStart);
     // Gecko browsers fire contextmenu *after* opening the menu, at
     // which point we can't mess with it anymore. Context menu is
     // handled in onMouseDown for Gecko.
@@ -262,18 +263,24 @@ var CodeMirror = (function() {
       if (!start) {if (e_target(e) == scroller) e_preventDefault(e); return;}
 
       if (!focused) onFocus();
-      e_preventDefault(e);
 
       var now = +new Date;
       if (lastDoubleClick > now - 400) {
+        e_preventDefault(e);
         return selectLine(start.line);
       } else if (lastClick > now - 400) {
         lastDoubleClick = now;
+        e_preventDefault(e);
         return selectWordAt(start);
       } else { lastClick = now; }
 
-      setCursor(start.line, start.ch, true);
       var last = start, going;
+      if (!posLess(start, sel.from) && !posLess(sel.to, start)) {
+        // Let the drag handler handle this.
+        return;
+      }
+      e_preventDefault(e);
+      setCursor(start.line, start.ch, true);
 
       function extend(e) {
         var cur = posFromMouse(e, true);
@@ -327,6 +334,13 @@ var CodeMirror = (function() {
         catch(e){}
       }
     }
+    function onDragStart(e) {
+      var txt = getSelection();
+      // This will reset escapeElement
+      htmlEscape(txt);
+      e.dataTransfer.setDragImage(escapeElement, 0, 0);
+      e.dataTransfer.setData("Text", txt);
+    }
     function onKeyDown(e) {
       if (!focused) onFocus();