fix multiselect mouse interaction issues

lib/ace/mouse/dragdrop_handler.js

@@ -384,6 +384,8 @@ function DragdropHandler(mouseHandler) {
         var button = e.getButton();
         var clickCount = e.domEvent.detail || 1;
         if (clickCount === 1 && button === 0 && inSelection) {
+            if (e.editor.inMultiSelectMode && (e.getAccelKey() || e.getShiftKey()))
+                return;
             this.mousedownEvent.time = Date.now();
             var eventTarget = e.domEvent.target || e.domEvent.srcElement;
             if ("unselectable" in eventTarget)
@@ -391,7 +393,7 @@ function DragdropHandler(mouseHandler) {
             if (editor.getDragDelay()) {
                 // https://code.google.com/p/chromium/issues/detail?id=286700
                 if (useragent.isWebKit) {
-                    self.cancelDrag = true;
+                    this.cancelDrag = true;
                     var mouseTarget = editor.container;
                     mouseTarget.draggable = true;
                 }

lib/ace/mouse/multi_select_handler.js

@@ -105,7 +105,8 @@ function onMouseDown(e) {
         }
 
         var oldRange = selection.rangeList.rangeAtPoint(pos);
-
+        
+        editor.$blockScrolling++;
         editor.once("mouseup", function() {
             var tmpSel = selection.toOrientedRange();
 
@@ -118,6 +119,7 @@ function onMouseDown(e) {
                 }
                 selection.addRange(tmpSel);
             }
+            editor.$blockScrolling--;
         });
 
     } else if (alt && button == 0) {