| columnsAddedHandler | Select handler invoked when columns are selected. |
| columns | A set of existing columns. This set can help populate the column selector. |
| mousePosition | Mouse position when the window needs to be opened. |
| activeColumnIndex | Any active column index that we pass back to the select handler. |
Opens an auxiliary column selector window to allow the user to search for a column to be added.
In example, the selected column could be added to an existing search property table.