Toolbar icons do not update when swapping sides

[DEinspanjer]

To reproduce:

1. Diff two folders
2. Select a file on the left side
3. Click the Swap icon on the toolbar
4. The file that you highlighted is now on the right (still highlighted)
5. Look for the "Copy to other side" icon.
6. Note that it is pointing in the wrong direction.
7. Unselect and reselect the file to correct the icon
8. If you click the icon in its bad state, you will see the copy dialog with the wrong side highlighted and disabled as well.

[Zoë]

This will be fixed in the next release.