[BZ#760371] Toggling "Flatten" should re-select the currently selected file

Submitted by Leo Wandersleb

Description

Using meld, I know I'm looking at build.gradle for example, but there is 20 files with that name in my repository with many files and folders in between, so it's a lot of scrolling to know what I'm looking at. (I'm merging a very old branch right now, so there is diffs all over the place.)

Expected behavior would be to see the path somewhere. In the status bar for example. There it could be consistent for the selected file in the tree view and the opened file in the file diff view.