diff --git a/Graphics/UI/Gtk/Abstract/Container.chs b/Graphics/UI/Gtk/Abstract/Container.chs
--- a/Graphics/UI/Gtk/Abstract/Container.chs
+++ b/Graphics/UI/Gtk/Abstract/Container.chs
@@ -415,7 +415,7 @@
 -- because toplevel windows can't leave space outside, they leave the space
 -- inside. The border is added on all sides of the container. To add space to
 -- only one side, one approach is to create a 'Alignment' widget, call
--- 'widgetSetUsize' to give it a size, and place it on the side of the
+-- 'widgetSetSizeRequest' to give it a size, and place it on the side of the
 -- container as a spacer.
 --
 containerSetBorderWidth :: ContainerClass self => self
diff --git a/Graphics/UI/Gtk/Abstract/Widget.chs b/Graphics/UI/Gtk/Abstract/Widget.chs
--- a/Graphics/UI/Gtk/Abstract/Widget.chs
+++ b/Graphics/UI/Gtk/Abstract/Widget.chs
@@ -232,6 +232,9 @@
   widgetHasScreen,
 #endif
   widgetGetSizeRequest,
+#if GTK_CHECK_VERSION(3,0,0)
+  widgetGetPreferredSize,
+#endif
   widgetSetChildVisible,
   widgetSetSizeRequest,
 #if GTK_CHECK_VERSION(2,4,0)
@@ -821,7 +824,7 @@
 
 -- | This function is only for use in widget implementations. Obtains the
 -- chached requisition information in the widget, unless someone has forced a
--- particular geometry on the widget (e.g. with 'widgetSetUsize'), in which
+-- particular geometry on the widget (e.g. with 'widgetSetSizeRequest'), in which
 -- case it returns that geometry instead of the widget's requisition.
 --
 -- This function differs from 'widgetSizeRequest' in that it retrieves the
@@ -2405,6 +2408,37 @@
   width <- peek widthPtr
   height <- peek heightPtr
   return (fromIntegral width, fromIntegral height)
+
+#if GTK_CHECK_VERSION(3,0,0)
+-- | Retrieves the minimum and natural size of a widget, taking into account the
+-- widget’s preference for height-for-width management.
+--
+-- This is used to retrieve a suitable size by container widgets which do not
+-- impose any restrictions on the child placement. It can be used to deduce
+-- toplevel window and menu sizes as well as child widgets in free-form containers
+-- such as GtkLayout.
+--
+-- Handle with care. Note that the natural height of a height-for-width widget
+-- will generally be a smaller size than the minimum height, since the required
+-- height for the natural width is generally smaller than the required height for
+-- the minimum width.
+--
+-- Use gtk_widget_get_preferred_height_and_baseline_for_width() if you want
+-- to support baseline alignment.
+--
+-- * Available since Gtk+ version 3.0
+--
+
+widgetGetPreferredSize :: WidgetClass self => self
+ -> IO (Requisition, Requisition) -- ^ @(minimumSize, naturalSize)@
+widgetGetPreferredSize self =
+  alloca $ \minReqPtr ->
+  alloca $ \natReqPtr -> do
+  {#call gtk_widget_get_preferred_size #} (toWidget self) (castPtr minReqPtr) (castPtr natReqPtr)
+  min <- peek minReqPtr
+  nat <- peek natReqPtr
+  return (min, nat)
+#endif
 
 -- %hash c:546d d:3c7f
 -- | Sets whether @widget@ should be mapped along with its when its parent is
diff --git a/Graphics/UI/Gtk/Misc/Viewport.chs b/Graphics/UI/Gtk/Misc/Viewport.chs
--- a/Graphics/UI/Gtk/Misc/Viewport.chs
+++ b/Graphics/UI/Gtk/Misc/Viewport.chs
@@ -82,6 +82,7 @@
   ) where
 
 import Control.Monad    (liftM)
+import Data.Maybe (fromMaybe)
 
 import System.Glib.FFI
 import System.Glib.Attributes
@@ -97,15 +98,15 @@
 -- | Creates a new 'Viewport' with the given adjustments.
 --
 viewportNew ::
-    Adjustment  -- ^ @hadjustment@ - horizontal adjustment.
- -> Adjustment  -- ^ @vadjustment@ - vertical adjustment.
+    Maybe Adjustment  -- ^ @hadjustment@ - horizontal adjustment.
+ -> Maybe Adjustment  -- ^ @vadjustment@ - vertical adjustment.
  -> IO Viewport
 viewportNew hadjustment vadjustment =
   makeNewObject mkViewport $
   liftM (castPtr :: Ptr Widget -> Ptr Viewport) $
   {# call unsafe viewport_new #}
-    hadjustment
-    vadjustment
+    (fromMaybe (Adjustment nullForeignPtr) hadjustment)
+    (fromMaybe (Adjustment nullForeignPtr) vadjustment)
 
 --------------------
 -- Methods
diff --git a/gtk.cabal b/gtk.cabal
--- a/gtk.cabal
+++ b/gtk.cabal
@@ -1,12 +1,12 @@
+cabal-version:  3.0
 Name:           gtk
-Version:        0.15.5
-License:        LGPL-2.1
+Version:        0.15.7
+License:        LGPL-2.1-only
 License-file:   COPYING
 Copyright:      (c) 2001-2010 The Gtk2Hs Team
 Author:         Axel Simon, Duncan Coutts and many others
 Maintainer:     gtk2hs-users@lists.sourceforge.net
 Build-Type:     Custom
-Cabal-Version:  >= 1.24
 Stability:      provisional
 homepage:       http://projects.haskell.org/gtk2hs/
 bug-reports:    https://github.com/gtk2hs/gtk2hs/issues
@@ -135,7 +135,7 @@
 
 custom-setup
   setup-depends: base >= 4.6,
-                 Cabal >= 1.24 && < 3.3,
+                 Cabal >= 2.0 && < 3.7,
                  gtk2hs-buildtools >= 0.13.2.0 && < 0.14
 
 Library
@@ -389,7 +389,7 @@
         else
           x-Types-Tag:  deprecated
         if os(windows)
-          cpp-options:    -DWIN32 -fno-exceptions
+          cpp-options:    -DWIN32
           cc-options:     -fno-exceptions
           extra-libraries: kernel32