Steps to reproduce:

1. Select a file in the Unstaged files area of the File Status tab.
CORRECT: => The diff window presents the differences of the UNSTAGED hunks

2. Click on Stage Hunk for a Hunk to be staged
CORRECT: => The diff window is updated to excluded the staged hunk and present the rest of the UNSTAGED hunks.

3. Click on the semi-staged file in the Staged Files area of the File Status tab.
CORRECT: => The diff window presents the differences of the STAGED hunks.

4. Select some staged lines and click on the Unstage Lines button or click on Unstage Hunk
INCORRECT: => The diff window presents the differences of the UNSTAGED hunks while the semi-staged file is selected in the Staged Files area.

5.INCORRECT: Even if the semi-staged file is re-selected the diff window is not updated (since the semi-staged file is already selected and there is no event triggered for change of selection).

6. WORKAROUND: Select another file anywhere and then select back the semi-staged file to get the correct updated view of the diff window.

7. EXPECTED: On unstaging of the lines selected either the semi-staged file should remain selected and the diff window be updated to exclude the unstaged lines (Preferable)

OR the semi-unstaged file should be selected and the diff window be update to show the unstaged hunks remaining

BUT NOT the semi-STAGED file to be selected and the diff window to present the UNSTAGED hunks.