git-gui: Fix semi-working shortcuts for unstage and revert

Make Ctrl+U for unstaging and Ctrl+J for reverting selection behave
more like Ctrl+T for adding.

They were working only when one area was focused (diff or commit message),
now they should work everywhere.

Acked-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Vitaly _Vi Shukela <vi0oss@gmail.com>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>

git-gui.sh

@@ -3715,6 +3715,8 @@ bind $ui_diff <$M1B-Key-v> {break}
 bind $ui_diff <$M1B-Key-V> {break}
 bind $ui_diff <$M1B-Key-a> {%W tag add sel 0.0 end;break}
 bind $ui_diff <$M1B-Key-A> {%W tag add sel 0.0 end;break}
+bind $ui_diff <$M1B-Key-j> {do_revert_selection;break}
+bind $ui_diff <$M1B-Key-J> {do_revert_selection;break}
 bind $ui_diff <Key-Up>     {catch {%W yview scroll -1 units};break}
 bind $ui_diff <Key-Down>   {catch {%W yview scroll  1 units};break}
 bind $ui_diff <Key-Left>   {catch {%W xview scroll -1 units};break}
@@ -3747,6 +3749,8 @@ bind .   <$M1B-Key-s> do_signoff
 bind .   <$M1B-Key-S> do_signoff
 bind .   <$M1B-Key-t> do_add_selection
 bind .   <$M1B-Key-T> do_add_selection
+bind .   <$M1B-Key-u> do_unstage_selection
+bind .   <$M1B-Key-U> do_unstage_selection
 bind .   <$M1B-Key-j> do_revert_selection
 bind .   <$M1B-Key-J> do_revert_selection
 bind .   <$M1B-Key-i> do_add_all