determine sorted column in setSortDescriptors:

Closes #1079

AppKit/CPTableView.j

@@ -2465,7 +2465,7 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
 - (void)_sendDataSourceSortDescriptorsDidChange:(CPArray)oldDescriptors
 {
     if (_implementedDataSourceMethods & CPTableViewDataSource_tableView_sortDescriptorsDidChange_)
-            [_dataSource tableView:self sortDescriptorsDidChange:oldDescriptors];
+        [_dataSource tableView:self sortDescriptorsDidChange:oldDescriptors];
 }
 
 
@@ -2543,13 +2543,7 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
     [newSortDescriptors removeObjectsInArray:outdatedDescriptors];
     [newSortDescriptors insertObject:newMainSortDescriptor atIndex:0];
 
-    // Update indicator image & highlighted column before
-    var image = [newMainSortDescriptor ascending] ? [self _tableHeaderSortImage] : [self _tableHeaderReverseSortImage];
-
-    [self setIndicatorImage:nil inTableColumn:_currentHighlightedTableColumn];
-    [self setIndicatorImage:image inTableColumn:tableColumn];
     [self setHighlightedTableColumn:tableColumn];
-
     [self setSortDescriptors:newSortDescriptors];
 }
 
@@ -2814,6 +2808,28 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
     return _verticalMotionCanDrag;
 }
 
+- (CPTableColumn)_tableColumnForSortDescriptor:(CPSortDescriptor)theSortDescriptor
+{
+    var tableColumns = [self tableColumns];
+
+    for (var i = 0; i < [tableColumns count]; i++)
+    {
+        var tableColumn = [tableColumns objectAtIndex:i],
+            sortDescriptorPrototype = [tableColumn sortDescriptorPrototype];
+
+        if (!sortDescriptorPrototype)
+            continue;
+
+        if ([sortDescriptorPrototype key] === [theSortDescriptor key]
+            && [sortDescriptorPrototype selector] === [theSortDescriptor selector])
+        {
+            return tableColumn;
+        }
+    }
+
+    return nil;
+}
+
 /*!
     Sets the table view's CPSortDescriptors objects in an array.
 
@@ -2821,7 +2837,7 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
 */
 - (void)setSortDescriptors:(CPArray)sortDescriptors
 {
-    var oldSortDescriptors = [self sortDescriptors],
+    var oldSortDescriptors = [[self sortDescriptors] copy],
         newSortDescriptors = nil;
 
     if (sortDescriptors == nil)
@@ -2834,6 +2850,25 @@ CPTableViewFirstColumnOnlyAutoresizingStyle = 5;
 
     _sortDescriptors = newSortDescriptors;
 
+    var oldColumn = nil,
+        newColumn = nil;
+
+    if ([newSortDescriptors count] > 0)
+    {
+        var newMainSortDescriptor = [newSortDescriptors objectAtIndex:0];
+        newColumn = [self _tableColumnForSortDescriptor:newMainSortDescriptor];
+    }
+
+    if ([oldSortDescriptors count] > 0)
+    {
+        var oldMainSortDescriptor = [oldSortDescriptors objectAtIndex:0];
+        oldColumn = [self _tableColumnForSortDescriptor:oldMainSortDescriptor];
+    }
+
+    var image = [newMainSortDescriptor ascending] ? [self _tableHeaderSortImage] : [self _tableHeaderReverseSortImage];
+    [self setIndicatorImage:nil inTableColumn:oldColumn];
+    [self setIndicatorImage:image inTableColumn:newColumn];
+
     [self _sendDataSourceSortDescriptorsDidChange:oldSortDescriptors];
 }