see Q501344
internal bool GetIsNonSortableEditor() {
if(ColumnEdit is RepositoryItemBlobBaseEdit ||
ColumnEdit is RepositoryItemPictureEdit ||
ColumnEdit is RepositoryItemSparklineEdit) return true;
return false;
}
I suppose that this code should look like the one below:
internal bool GetIsNonSortableEditor() {
return ColumnEdit.GetIsNonSortableEditor();
}