Hugo Lefeuvre authored Apr 11, 2018 and Sébastien Blin committed Apr 11, 2018

The Download folder button (Settings/General) is implemented as a
FileChooserButton, which makes the ChooseFolder dialog non-modal by
default. While this can be meaningful in many cases, it is a very
confusing feature for Ring users.

In this patch, we:
a) Stop using FileChooserButton (it is very difficult to have modal
   dialogs with this class)

b) Instead opt for a classical button with dedicated callback handling
   dialog stuff

In order to make the dialog modal, a reference to the main window is
needed by the callback. Since the GeneralSettingsView inherits from
GtkScrolledWindow, this reference is not stored by default into the
class. In order to address this issue we implement a property system
and store the main window reference into the private variables of the
class.

Change-Id: I8ea4fb7fa32d289abffc44ee80215f08c155cbd6
Tuleap: #1852
Reviewed-by: Sébastien Blin <sebastien.blin@savoirfairelinux.com>