investigate diff should allow choosing commit rather that previous only

Currently, when investigating a file (right click file/investigate), the Diff view :

only shows the diff between the selected file (New contents) and the previous version (Old contents).

It would be nice(r) if it was possible to select a previous version in the Navigation pane e.g:

and have that replace the Old contents so one could compare (i.e. not unlike the functionality from using the working tree view and doing it there - just focused more in the Investigate window as then one is looking at the one file rather than the whole commit)