is_blank_at_pos
Description:
Determine whether the point (x, y) in this is blank, that is no cell content nor an
       expander arrow is drawn at the location.
Use [class@Gtk.ListView] or [class@Gtk.ColumnView] instead
If so, the location can be considered as the background. You might wish to take special action on clicks on the background, such as clearing a current selection, having a custom context menu or starting rubber banding.
The x and y coordinate that are provided must be relative to bin_window coordinates. Widget-relative coordinates must
       be converted using convert_widget_to_bin_window_coords
      .
For converting widget coordinates (eg. the ones you get from GtkWidget:GtkTreeView:query-tooltip), please see 
      convert_widget_to_bin_window_coords.
The path, column, cell_x and cell_y arguments will be filled in likewise as for 
      get_path_at_pos. Please see 
      get_path_at_pos for more information.
Parameters:
| this | A `GtkTreeView` | 
| x | The x position to be identified (relative to bin_window) | 
| y | The y position to be identified (relative to bin_window) | 
| path | A pointer to a `GtkTreePath` pointer to be filled in | 
| column | A pointer to a `GtkTreeViewColumn` pointer to be filled in | 
| cell_x | A pointer where the X coordinate relative to the cell can be placed | 
| cell_y | A pointer where the Y coordinate relative to the cell can be placed | 
Returns:
| true if the area at the given coordinates is blank, false otherwise. |