require at least gtk3 3.18.0 to build and run gtk3 bits

Change-Id: I02efb169ba1d0756d2d9c4b77c3c2b58e48c4a82
Reviewed-on: https://gerrit.libreoffice.org/45727Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

configure.ac

@@ -9724,7 +9724,7 @@ if test "x$enable_gtk3" = "xyes"; then
         AC_MSG_ERROR([System cairo required for gtk3 support, do not combine --enable-gtk3 with --without-system-cairo])
     fi
     : ${with_system_cairo:=yes}
-    PKG_CHECK_MODULES(GTK3, gtk+-3.0 >= 3.16 gtk+-unix-print-3.0 gmodule-no-export-2.0 glib-2.0 >= 2.38 cairo, ENABLE_GTK3="TRUE", ENABLE_GTK3="")
+    PKG_CHECK_MODULES(GTK3, gtk+-3.0 >= 3.18 gtk+-unix-print-3.0 gmodule-no-export-2.0 glib-2.0 >= 2.38 cairo, ENABLE_GTK3="TRUE", ENABLE_GTK3="")
     if test "x$ENABLE_GTK3" = "xTRUE"; then
         R="gtk3"
         dnl Avoid installed by unpackaged files for now.

vcl/unx/gtk/gtkinst.cxx

@@ -82,7 +82,7 @@ extern "C"
             XInitThreads();
 
 #if GTK_CHECK_VERSION(3,0,0)
-        if (gtk_minor_version < 16)
+        if (gtk_minor_version < 18)
         {
             g_warning("require a newer gtk than 3.%d for theme expectations", gtk_minor_version);
             return nullptr;

vcl/unx/gtk3/gtk3gtkframe.cxx

@@ -1903,11 +1903,7 @@ void GtkSalFrame::SetScreen( unsigned int nNewScreen, SetType eType, tools::Rect
             gtk_window_fullscreen(GTK_WINDOW(m_pWindow));
         else
         {
-#if GTK_CHECK_VERSION(3,18,0)
             gtk_window_fullscreen_on_monitor(GTK_WINDOW(m_pWindow), pScreen, nMonitor);
-#else
-            gtk_window_fullscreen(GTK_WINDOW(m_pWindow));
-#endif
         }
 
     }
@@ -2281,10 +2277,8 @@ KeyIndicatorState GtkSalFrame::GetIndicatorState()
         nState |= KeyIndicatorState::CAPSLOCK;
     if (gdk_keymap_get_num_lock_state(pKeyMap))
         nState |= KeyIndicatorState::NUMLOCK;
-#if GTK_CHECK_VERSION(3,18,0)
     if (gdk_keymap_get_scroll_lock_state(pKeyMap))
         nState |= KeyIndicatorState::SCROLLLOCK;
-#endif
 
     return nState;
 }