take into account that undos can have inserts and removes mixed

lib/ace/edit_session.js

@@ -536,15 +536,7 @@ var EditSession = function(text, mode) {
         this.doc.revertDeltas(deltas);
         this.$fromUndo = false;
 
-        // update the selection
+        this.$setUndoSelection(deltas, true);
-        var firstDelta = deltas[0];
-        var lastDelta = deltas[deltas.length-1];
-
-        this.selection.clearSelection();
-        if (firstDelta.action == "insertText" || firstDelta.action == "insertLines")
-            this.selection.moveCursorToPosition(firstDelta.range.start);
-        if (firstDelta.action == "removeText" || firstDelta.action == "removeLines")
-            this.selection.setSelectionRange(Range.fromPoints(lastDelta.range.start, firstDelta.range.end));
     },
 
     this.redoChanges = function(deltas) {
@@ -555,17 +547,55 @@ var EditSession = function(text, mode) {
         this.doc.applyDeltas(deltas);
         this.$fromUndo = false;
 
-        // update the selection
+        this.$setUndoSelection(deltas, false);
-        var firstDelta = deltas[0];
-        var lastDelta = deltas[deltas.length-1];
-
-        this.selection.clearSelection();
-        if (firstDelta.action == "insertText" || firstDelta.action == "insertLines")
-            this.selection.setSelectionRange(Range.fromPoints(firstDelta.range.start, lastDelta.range.end));
-        if (firstDelta.action == "removeText" || firstDelta.action == "removeLines")
-            this.selection.moveCursorToPosition(lastDelta.range.start);
     },
 
+    this.$setUndoSelection = function(deltas, isUndo) {
+        // invert deltas is they are an undo
+        if (isUndo)
+            deltas = deltas.map(function(delta) {
+                var d = {
+                    range: delta.range
+                }
+                if (delta.action == "insertText" || delta.action == "insertLines")
+                    d.action = "removeText"
+                else
+                    d.action = "insertText"
+                return d;
+            }).reverse();
+
+
+        var actions = [{}];
+        
+        // collapse insert and remove operations
+        for (var i=0; i<deltas.length; i++) {
+            var delta = deltas[i];
+            var isInsert = delta.action == "insertText" || delta.action == "insertLines";
+            var action = actions[actions.length-1];
+            if (action.isInsert !== isInsert) {
+                actions.push({
+                    isInsert: isInsert,
+                    start: isInsert ? delta.range.start : delta.range.end,
+                    end: isInsert ? delta.range.end : delta.range.start
+                })
+            }
+            else {
+                if (isInsert)    
+                    action.end = delta.range.end;
+                else
+                    action.start = delta.range.start;
+            }
+        }
+        
+        // update selection based on last operation
+        this.selection.clearSelection();
+        var action = actions[actions.length-1];
+        if (action.isInsert) 
+            this.selection.setSelectionRange(Range.fromPoints(action.start, action.end));
+        else 
+            this.selection.moveCursorToPosition(action.start);
+    },
+    
     this.replace = function(range, text) {
         return this.doc.replace(range, text);
     };
@@ -1192,4 +1222,4 @@ var EditSession = function(text, mode) {
 }).call(EditSession.prototype);
 
 exports.EditSession = EditSession;
-});
+});