Comment 11 for bug 1649530

Using 0 as the default value seems not to work:

/home/lminiero/Scaricati/lifeograph/src/app_window.cpp: In member function ‘void LIFEO::AppWindow::login()’:
/home/lminiero/Scaricati/lifeograph/src/app_window.cpp:461:80: error: invalid conversion from ‘int’ to ‘Gtk::IconLookupFlags’ [-fpermissive]
           Gtk::IconInfo ii = theme->lookup_icon( "filter-16-symbolic", 16, 0 );

Casting 0 to (IconLookupFlags) did the trick for me instead:

           Gtk::IconInfo ii = theme->lookup_icon( "filter-16-symbolic", 16, (IconLookupFlags)0 );

Just compiled, installed, started and upgraded my diaries, and everything seems to be working as expected, thanks!