Restore org.gnome.desktop.interface cursor-theme

[quozl]

The Sugar cursor affects the GNOME desktop environment.

This is caused by https://github.com/sugarlabs/sugar/blob/master/src/jarabe/main.py#L205 where the GNOME desktop cursor theme is changed to the Sugar theme.

Workaround is to use gsettings to change cursor-theme in org.gnome.desktop.interface back to what it was. Or you can use dconf to reset all settings, but that has many side-effects.

• read the value of cursor-theme before changing it in the _start_window_manager function,
• keep the Gio.Settings instance instead of deleting at end of the _start_window_manager function,
• restore the old value in the _stop_window_manager function.

This should fix the problem for future users.

[kushagra98]

#828 Checked on my machine and works perfectly 😃