How to make Sort Icon visible for all columns in GWT

I am creating an application where I need to do sort and search on header. I have used column.setSortable(true); and Creating sort handler. Again on other side I have created a custom header which will show textbox when clicking. I want to implement it like there will be sort icons clicking on that will sort while clicking on column label will open textbox. Can anyone suggest how I can make sort icons visible in all the columns.

Currently when I click any column sort icon gets visible on that only.

Done fixing this. I have used overriding onPreviewColumnSortEvent and implemented is as below

    @Override
public boolean onPreviewColumnSortEvent( Context context, Element elem, NativeEvent event )
{
    if ( clickableTableCell.getColumnType().equals( ColumnType.TEXTBOX ) ) {
        if ( sortFlag ) {
            sortFlag = false;
        } else {
            sortFlag = true;
        }
    }
    return sortFlag;
}