convert_bin_window_to_tree_coords
Description:
Converts bin_window coordinates to coordinates for the tree (the full scrollable area of the tree).
Note: 
      
        
    
    Use [class@Gtk.ListView] or [class@Gtk.ColumnView] instead
Parameters:
| this | a `GtkTreeView` | 
| bx | X coordinate relative to bin_window | 
| by | Y coordinate relative to bin_window | 
| tx | return location for tree X coordinate | 
| ty | return location for tree Y coordinate |