Use abstract newtypes to hide pointers

5 files changed, 111 insertions, 41 deletions

diff --git a/src/Gtk/Signal.icl b/src/Gtk/Signal.icl
index 543c7a2..be019b5 100644
--- a/src/Gtk/Signal.icl
+++ b/src/Gtk/Signal.icl
@@ -49,7 +49,7 @@ installSignalHandler handler widget =
 		& signal_handlers = 'Data.Map'.put (st.signal_counter+1) handler_internal st.signal_handlers
 		, signal_counter  = st.signal_counter+1
 		}) >>= \{signal_counter=id} ->
-	let (GtkWidget w) = gtkWidget widget in
+	let w = toPtr widget in
 	toState (g_signal_connect w (signalName handler) (callback handler_internal) id) >>|
 	pure widget
 where
diff --git a/src/Gtk/Widgets.dcl b/src/Gtk/Widgets.dcl
index 957838b..bc1e0af 100644
--- a/src/Gtk/Widgets.dcl
+++ b/src/Gtk/Widgets.dcl
@@ -12,12 +12,6 @@ definition module Gtk.Widgets
  * example, all subclasses of `GtkWidget` implement the `gtkWidget` class, and
  * common methods of the `GtkWidget` class correspond to overloaded functions
  * in Clean.
- *
- * NB: The types of widgets are exported here because (1) newtypes cannot be
- * abstract and (2) they must be able to implement `TC` so that they can be
- * shared (see `Gtk.Shares`). When the compiler supports abstract newtypes and
- * `TC` instantiation of hidden types, the implementation of these types may
- * be removed from the definition module; do not rely on it!
  */
 
 from StdMaybe import :: Maybe
@@ -41,7 +35,7 @@ from Gtk.Types import
  * A `GtkAccelGroup` is needed for a `GtkAccelerator`. 'Accelerator' is Gtk's
  * term for what most people call shortcuts, i.e. `Ctrl`-`S`, etc.
  */
-:: GtkAccelGroup =: GtkAccelGroup Pointer
+:: GtkAccelGroup (=: GtkAccelGroup Pointer)
 
 newAccelGroup :: !w -> GtkM GtkAccelGroup | gtkWindow w
 
@@ -54,7 +48,7 @@ newAccelGroup :: !w -> GtkM GtkAccelGroup | gtkWindow w
 :: GtkAccelerator = Accelerator !GtkAccelGroup !String ![GdkModifier]
 
 //* An action bar typically holds a number of buttons.
-:: GtkActionBar =: GtkActionBar Pointer
+:: GtkActionBar (=: GtkActionBar Pointer)
 instance gtkWidget GtkActionBar
 
 newActionBar :: GtkM GtkActionBar
@@ -63,7 +57,7 @@ newActionBar :: GtkM GtkActionBar
 packActionBar :: !GtkActionBar !GtkDirection !w -> GtkM w | gtkWidget w
 
 //* A box holds a number of child widgets in some direction with spacing.
-:: GtkBox =: GtkBox Pointer
+:: GtkBox (=: GtkBox Pointer)
 instance gtkWidget GtkBox
 instance gtkContainer GtkBox
 instance gtkOrientable GtkBox
@@ -79,7 +73,7 @@ packBox :: !GtkBox !GtkDirection !GtkExpand !w -> GtkM w | gtkWidget w
 
 instance tune GtkBox GtkSpacing
 
-:: GtkButton =: GtkButton Pointer
+:: GtkButton (=: GtkButton Pointer)
 instance gtkWidget GtkButton
 
 /**
@@ -90,17 +84,19 @@ instance gtkWidget GtkButton
  */
 newButtonFromIconName :: !String -> GtkM GtkButton
 
-:: GtkContainer =: GtkContainer Pointer
+:: GtkContainer (=: GtkContainer Pointer)
 
 class gtkContainer a :: !a -> GtkContainer
 
 instance gtkWidget GtkContainer
 instance gtkContainer GtkContainer
 
+unsafeToContainer :: !Pointer -> GtkContainer
+
 addToContainer :: !c !w -> GtkM w | gtkWidget w & gtkContainer c
 
 //* A dialog is a popup window.
-:: GtkDialog =: GtkDialog Pointer
+:: GtkDialog (=: GtkDialog Pointer)
 
 class gtkDialog a :: !a -> GtkDialog
 
@@ -142,13 +138,15 @@ newMessageDialog :: !GtkWindow !GtkMessageType !GtkButtonsType !String -> GtkM G
 getFileWithDialog :: !GtkWindow !GtkFileChooserAction !(Maybe String) -> GtkM (Maybe FilePath)
 
 //* An entry is a simple text field. Subclasses allow more advanced input.
-:: GtkEntry =: GtkEntry Pointer
+:: GtkEntry (=: GtkEntry Pointer)
 
 class gtkEntry a :: !a -> GtkEntry
 
 instance gtkWidget GtkEntry
 instance gtkEntry GtkEntry
 
+unsafeToEntry :: !Pointer -> GtkEntry
+
 newEntry :: GtkM GtkEntry
 getText :: !e -> GtkM String | gtkEntry e
 
@@ -163,7 +161,7 @@ instance tune GtkEntry GtkEntryCompletion
  * `GtkListStore` that is filtered with the default match function. It is
  * possible to tune the completion method with a `GtkCompletionMode`, however.
  */
-:: GtkEntryCompletion =: GtkEntryCompletion Pointer
+:: GtkEntryCompletion (=: GtkEntryCompletion Pointer)
 
 newEntryCompletion :: GtkM GtkEntryCompletion
 
@@ -174,7 +172,7 @@ instance tune GtkEntryCompletion GtkListStore
 instance tune GtkEntryCompletion GtkCompletionMode
 
 //* A frame holds a single child, with a border and an optional title.
-:: GtkFrame =: GtkFrame Pointer
+:: GtkFrame (=: GtkFrame Pointer)
 instance gtkWidget GtkFrame
 instance gtkContainer GtkFrame
 
@@ -187,7 +185,7 @@ framed :: !GtkTitle !(GtkM w) -> GtkM (w, GtkFrame) | gtkWidget w
  * A grid is a generalized table, allowing outlining child widget positions to
  * each other.
  */
-:: GtkGrid =: GtkGrid Pointer
+:: GtkGrid (=: GtkGrid Pointer)
 instance gtkWidget GtkGrid
 
 newGrid :: GtkM GtkGrid
@@ -200,7 +198,7 @@ newGrid :: GtkM GtkGrid
 attachGrid :: !GtkGrid !(!Int,!Int) !(!Int,!Int) !w -> GtkM w | gtkWidget w
 
 //* A label is used to display a small or medium amount of text.
-:: GtkLabel =: GtkLabel Pointer
+:: GtkLabel (=: GtkLabel Pointer)
 instance gtkWidget GtkLabel
 
 newLabel :: GtkM GtkLabel
@@ -210,7 +208,7 @@ instance tune GtkLabel GtkText
  * A list store holds values in a list. It is used in several places, like for
  * `GtkEntryCompletion` and `GtkTreeView`.
  */
-:: GtkListStore =: GtkListStore Pointer
+:: GtkListStore (=: GtkListStore Pointer)
 
 //* Create a new list store where rows are lists of values of the given types.
 newListStore :: ![GType] -> GtkM GtkListStore
@@ -228,7 +226,7 @@ swapItems :: !Int !Int !GtkListStore -> GtkM Bool
  * A menu provides actions to the user. `GtkMenu` by itself is useful to create
  * sub-menus (see `setSubMenu`). For a top-level menu, see `GtkMenuBar`.
  */
-:: GtkMenu =: GtkMenu Pointer
+:: GtkMenu (=: GtkMenu Pointer)
 instance gtkWidget GtkMenu
 
 newMenu :: GtkM GtkMenu
@@ -237,7 +235,7 @@ newMenu :: GtkM GtkMenu
  * A menu bar is usually placed at the top of a window, providing actions to
  * the user.
  */
-:: GtkMenuBar =: GtkMenuBar Pointer
+:: GtkMenuBar (=: GtkMenuBar Pointer)
 instance gtkWidget GtkMenuBar
 
 newMenuBar :: GtkM GtkMenuBar
@@ -246,7 +244,7 @@ newMenuBar :: GtkM GtkMenuBar
  * A menu item is an item in a menu. Attach an `ActivateHandler` or set a
  * sub-menu with `setSubMenu`.
  */
-:: GtkMenuItem =: GtkMenuItem Pointer
+:: GtkMenuItem (=: GtkMenuItem Pointer)
 
 class gtkMenuItem a :: !a -> GtkMenuItem
 
@@ -259,7 +257,7 @@ newMenuItem :: !String -> GtkM GtkMenuItem
 setSubMenu :: !mi !GtkMenu -> GtkM GtkMenu | gtkMenuItem mi
 
 //* A check menu item is a menu item with a checkbox.
-:: GtkCheckMenuItem =: GtkCheckMenuItem Pointer
+:: GtkCheckMenuItem (=: GtkCheckMenuItem Pointer)
 instance gtkWidget GtkCheckMenuItem
 instance gtkMenuItem GtkCheckMenuItem
 
@@ -272,14 +270,14 @@ isActive :: !GtkCheckMenuItem -> GtkM Bool
 setActive :: !Bool !GtkCheckMenuItem -> GtkM GtkCheckMenuItem
 
 //* A separator menu item draws as a simple line to group other items together.
-:: GtkSeparatorMenuItem =: GtkSeparatorMenuItem Pointer
+:: GtkSeparatorMenuItem (=: GtkSeparatorMenuItem Pointer)
 instance gtkWidget GtkSeparatorMenuItem
 instance gtkMenuItem GtkSeparatorMenuItem
 
 newSeparatorMenuItem :: GtkM GtkSeparatorMenuItem
 
 //* This is an interface for widgets that hold a collection of menu items.
-:: GtkMenuShell =: GtkMenuShell Pointer
+:: GtkMenuShell (=: GtkMenuShell Pointer)
 instance gtkWidget GtkMenuShell
 
 class gtkMenuShell a :: !a -> GtkMenuShell
@@ -288,14 +286,14 @@ instance gtkMenuShell GtkMenu, GtkMenuBar, GtkMenuShell
 appendToMenuShell :: !s !mi -> GtkM mi | gtkMenuShell s & gtkMenuItem mi
 
 //* This is an interface for widgets of which the children can be oriented.
-:: GtkOrientable =: GtkOrientable Pointer
+:: GtkOrientable (=: GtkOrientable Pointer)
 
 class gtkOrientable a :: !a -> GtkOrientable
 
 instance tune o GtkOrientation | gtkOrientable o
 
 //* A paned holds two children, with a (usually moveable) handle in between.
-:: GtkPaned =: GtkPaned Pointer
+:: GtkPaned (=: GtkPaned Pointer)
 instance gtkWidget GtkPaned
 instance gtkContainer GtkPaned
 
@@ -307,7 +305,7 @@ packPane2 :: !GtkPaned !GtkResize !GtkShrink !w -> GtkM w | gtkWidget w
  * A scrolled window holds a single child and uses a scrollbar if it does not
  * fit in the outer dimensions.
  */
-:: GtkScrolledWindow =: GtkScrolledWindow Pointer
+:: GtkScrolledWindow (=: GtkScrolledWindow Pointer)
 instance gtkWidget GtkScrolledWindow
 instance gtkContainer GtkScrolledWindow
 
@@ -317,20 +315,20 @@ instance tune GtkScrolledWindow (GtkScrollbarPolicy, GtkScrollbarPolicy)
 where tune :: !(!GtkScrollbarPolicy, !GtkScrollbarPolicy) !GtkScrolledWindow -> GtkM GtkScrolledWindow
 
 //* A search entry is a special entry with a search icon and clear button.
-:: GtkSearchEntry =: GtkSearchEntry Pointer
+:: GtkSearchEntry (=: GtkSearchEntry Pointer)
 instance gtkWidget GtkSearchEntry
 instance gtkEntry GtkSearchEntry
 
 newSearchEntry :: GtkM GtkSearchEntry
 
 //* A separator is a simple line, allowing for separation between widgets.
-:: GtkSeparator =: GtkSeparator Pointer
+:: GtkSeparator (=: GtkSeparator Pointer)
 instance gtkWidget GtkSeparator
 
 newSeparator :: !GtkOrientation -> GtkM GtkSeparator
 
 //* A spinner is an animated widget signaling indefinite progress.
-:: GtkSpinner =: GtkSpinner Pointer
+:: GtkSpinner (=: GtkSpinner Pointer)
 instance gtkWidget GtkSpinner
 
 newSpinner :: GtkM GtkSpinner
@@ -338,14 +336,14 @@ startSpinner :: !GtkSpinner -> GtkM GtkSpinner
 stopSpinner :: !GtkSpinner -> GtkM GtkSpinner
 
 //* A text buffer is viewed by a `GtkTextView`; updates occur on this type.
-:: GtkTextBuffer =: GtkTextBuffer Pointer
+:: GtkTextBuffer (=: GtkTextBuffer Pointer)
 
 instance tune GtkTextBuffer GtkText
 instance tune GtkTextBuffer GtkMarkup
 insertAtCursor :: !String !GtkTextBuffer -> GtkM GtkTextBuffer
 
 //* A text view holds a larger amount of text than a `GtkLabel`.
-:: GtkTextView =: GtkTextView Pointer
+:: GtkTextView (=: GtkTextView Pointer)
 instance gtkWidget GtkTextView
 instance gtkContainer GtkTextView
 
@@ -355,7 +353,7 @@ getTextBuffer :: !GtkTextView -> GtkTextBuffer
 instance tune GtkTextView GtkWrapMode
 
 //* A tree view is a view on a `GtkListStore` with customizable columns.
-:: GtkTreeView =: GtkTreeView Pointer
+:: GtkTreeView (=: GtkTreeView Pointer)
 instance gtkWidget GtkTreeView
 
 newTreeView :: !GtkListStore -> GtkM GtkTreeView
@@ -381,12 +379,15 @@ getPathToSelection :: !GtkTreeView -> GtkM (Maybe [Int])
 selectPath :: ![Int] !GtkTreeView -> GtkM Bool
 
 //* This is an abstract class; every GUI element is a widget.
-:: GtkWidget =: GtkWidget Pointer
+:: GtkWidget (=: GtkWidget Pointer)
 
 class gtkWidget a :: !a -> GtkWidget
 
 instance gtkWidget GtkWidget
 
+toPtr :: !w -> Pointer | gtkWidget w
+unsafeToWidget :: !Pointer -> GtkWidget
+
 show :: !w -> GtkM w | gtkWidget w
 hide :: !w -> GtkM w | gtkWidget w
 
@@ -412,7 +413,7 @@ instance tune w GtkAccelerator | gtkWidget w
 instance tune w GtkSizeRequest | gtkWidget w
 
 //* A window is a top-level element, holding a single child widget.
-:: GtkWindow =: GtkWindow Pointer
+:: GtkWindow (=: GtkWindow Pointer)
 
 class gtkWindow a :: !a -> GtkWindow
 
diff --git a/src/Gtk/Widgets.icl b/src/Gtk/Widgets.icl
index 702ea0e..41aadab 100644
--- a/src/Gtk/Widgets.icl
+++ b/src/Gtk/Widgets.icl
@@ -15,6 +15,8 @@ import Gtk
 import Gdk.Internal
 import Gtk.Internal
 
+:: GtkAccelGroup =: GtkAccelGroup Pointer
+
 newAccelGroup :: !w -> GtkM GtkAccelGroup | gtkWindow w
 newAccelGroup window =
 	let (GtkWindow w) = gtkWindow window in
@@ -22,6 +24,8 @@ newAccelGroup window =
 	toState (gtk_window_add_accel_group w ag) >>|
 	pure (GtkAccelGroup ag)
 
+:: GtkActionBar =: GtkActionBar Pointer
+
 instance gtkWidget GtkActionBar where gtkWidget (GtkActionBar ab) = GtkWidget ab
 
 newActionBar :: GtkM GtkActionBar
@@ -38,6 +42,8 @@ packActionBar (GtkActionBar b) dir widget =
 			w) >>|
 	pure widget
 
+:: GtkBox =: GtkBox Pointer
+
 instance gtkWidget GtkBox where gtkWidget (GtkBox b) = GtkWidget b
 instance gtkContainer GtkBox where gtkContainer (GtkBox b) = GtkContainer b
 instance gtkOrientable GtkBox where gtkOrientable (GtkBox b) = GtkOrientable b
@@ -60,6 +66,8 @@ where
 		toState (gtk_box_set_spacing b s) >>|
 		pure box
 
+:: GtkButton =: GtkButton Pointer
+
 instance gtkWidget GtkButton where gtkWidget (GtkButton b) = GtkWidget b
 
 newButtonFromIconName :: !String -> GtkM GtkButton
@@ -67,9 +75,14 @@ newButtonFromIconName icon =
 	toStateR (gtk_button_new_from_icon_name icon (toInt ButtonIconSize)) >>= \b ->
 	show (GtkButton b)
 
+:: GtkContainer =: GtkContainer Pointer
+
 instance gtkWidget GtkContainer where gtkWidget (GtkContainer c) = GtkWidget c
 instance gtkContainer GtkContainer where gtkContainer c = c
 
+unsafeToContainer :: !Pointer -> GtkContainer
+unsafeToContainer c = GtkContainer c
+
 addToContainer :: !c !w -> GtkM w | gtkWidget w & gtkContainer c
 addToContainer container widget =
 	let
@@ -79,6 +92,8 @@ addToContainer container widget =
 	toState (gtk_container_add c w) >>|
 	pure widget
 
+:: GtkDialog =: GtkDialog Pointer
+
 instance gtkWidget GtkDialog where gtkWidget (GtkDialog d) = GtkWidget d
 instance gtkContainer GtkDialog where gtkContainer (GtkDialog d) = GtkContainer d
 instance gtkWindow GtkDialog where gtkWindow (GtkDialog d) = GtkWindow d
@@ -146,9 +161,14 @@ where
 				destroy dialog >>|
 				pure Nothing
 
+:: GtkEntry =: GtkEntry Pointer
+
 instance gtkWidget GtkEntry where gtkWidget (GtkEntry e) = GtkWidget e
 instance gtkEntry GtkEntry where gtkEntry e = e
 
+unsafeToEntry :: !Pointer -> GtkEntry
+unsafeToEntry e = GtkEntry e
+
 newEntry :: GtkM GtkEntry
 newEntry =
 	toStateR gtk_entry_new >>= \e ->
@@ -166,6 +186,8 @@ where
 		toState (gtk_entry_set_text e text) >>|
 		pure entry
 
+:: GtkEntryCompletion =: GtkEntryCompletion Pointer
+
 instance tune GtkEntry GtkEntryCompletion
 where
 	tune (GtkEntryCompletion ec) entry=:(GtkEntry e) =
@@ -175,7 +197,6 @@ where
 newEntryCompletion :: GtkM GtkEntryCompletion
 newEntryCompletion =
 	toStateR gtk_entry_completion_new >>= \ec ->
-	toState (gtk_entry_completion_set_inline_selection ec True) >>| // TODO
 	pure (GtkEntryCompletion ec)
 
 setTextColumn :: !Int !GtkEntryCompletion -> GtkM GtkEntryCompletion
@@ -199,6 +220,8 @@ where
 			InlineSelection    -> gtk_entry_completion_set_inline_selection ec True
 			NoInlineSelection  -> gtk_entry_completion_set_inline_selection ec False
 
+:: GtkFrame =: GtkFrame Pointer
+
 instance gtkWidget GtkFrame where gtkWidget (GtkFrame f) = GtkWidget f
 instance gtkContainer GtkFrame where gtkContainer (GtkFrame f) = GtkContainer f
 
@@ -217,6 +240,8 @@ framed title widgetf =
 	widgetf >>= \widget ->
 	tuple widget <$> newFrame title widget
 
+:: GtkGrid =: GtkGrid Pointer
+
 instance gtkWidget GtkGrid where gtkWidget (GtkGrid g) = GtkWidget g
 
 newGrid :: GtkM GtkGrid
@@ -230,6 +255,8 @@ attachGrid (GtkGrid g) (left,top) (width,height) widget =
 	toState (gtk_grid_attach g w left top width height) >>|
 	pure widget
 
+:: GtkLabel =: GtkLabel Pointer
+
 instance gtkWidget GtkLabel where gtkWidget (GtkLabel l) = GtkWidget l
 
 newLabel :: GtkM GtkLabel
@@ -243,6 +270,8 @@ where
 		toState (gtk_label_set_markup l text) >>|
 		pure label
 
+:: GtkListStore =: GtkListStore Pointer
+
 newListStore :: ![GType] -> GtkM GtkListStore
 newListStore types =
 	toStateR (gtk_list_store_newv {toInt t \\ t <- types}) >>= \s ->
@@ -279,6 +308,8 @@ swapItems a b (GtkListStore s) =
 		(toState (gtk_list_store_swap s iter_a iter_b) >>| pure True)
 		(pure False)
 
+:: GtkMenu =: GtkMenu Pointer
+
 instance gtkWidget GtkMenu where gtkWidget (GtkMenu m) = GtkWidget m
 
 newMenu :: GtkM GtkMenu
@@ -286,6 +317,8 @@ newMenu =
 	toStateR gtk_menu_new >>= \m ->
 	show (GtkMenu m)
 
+:: GtkMenuBar =: GtkMenuBar Pointer
+
 instance gtkWidget GtkMenuBar where gtkWidget (GtkMenuBar mb) = GtkWidget mb
 
 newMenuBar :: GtkM GtkMenuBar
@@ -293,6 +326,8 @@ newMenuBar =
 	toStateR gtk_menu_bar_new >>= \mb ->
 	show (GtkMenuBar mb)
 
+:: GtkMenuItem =: GtkMenuItem Pointer
+
 instance gtkWidget GtkMenuItem where gtkWidget (GtkMenuItem mi) = GtkWidget mi
 instance gtkMenuItem GtkMenuItem where gtkMenuItem mi = mi
 
@@ -309,6 +344,8 @@ setSubMenu item menu=:(GtkMenu m) =
 	toState (gtk_menu_item_set_submenu mi m) >>|
 	pure menu
 
+:: GtkCheckMenuItem =: GtkCheckMenuItem Pointer
+
 instance gtkWidget GtkCheckMenuItem where gtkWidget (GtkCheckMenuItem cmi) = GtkWidget cmi
 instance gtkMenuItem GtkCheckMenuItem where gtkMenuItem (GtkCheckMenuItem cmi) = GtkMenuItem cmi
 
@@ -327,6 +364,8 @@ setActive active item=:(GtkCheckMenuItem cmi) =
 	toState (gtk_check_menu_item_set_active cmi active) >>|
 	pure item
 
+:: GtkSeparatorMenuItem =: GtkSeparatorMenuItem Pointer
+
 instance gtkWidget GtkSeparatorMenuItem where gtkWidget (GtkSeparatorMenuItem smi) = GtkWidget smi
 instance gtkMenuItem GtkSeparatorMenuItem where gtkMenuItem (GtkSeparatorMenuItem smi) = GtkMenuItem smi
 
@@ -335,6 +374,8 @@ newSeparatorMenuItem =
 	toStateR gtk_separator_menu_item_new >>= \smi ->
 	show (GtkSeparatorMenuItem smi)
 
+:: GtkMenuShell =: GtkMenuShell Pointer
+
 instance gtkWidget GtkMenuShell where gtkWidget (GtkMenuShell ms) = GtkWidget ms
 
 instance gtkMenuShell GtkMenu where gtkMenuShell (GtkMenu m) = GtkMenuShell m
@@ -350,6 +391,8 @@ appendToMenuShell shell item =
 	toState (gtk_menu_shell_append ms mi) >>|
 	pure item
 
+:: GtkOrientable =: GtkOrientable Pointer
+
 instance tune o GtkOrientation | gtkOrientable o
 where
 	tune orientation orientable =
@@ -357,6 +400,8 @@ where
 		toState (gtk_orientable_set_orientation o orientation=:Vertical) >>|
 		pure orientable
 
+:: GtkPaned =: GtkPaned Pointer
+
 instance gtkWidget GtkPaned where gtkWidget (GtkPaned p) = GtkWidget p
 instance gtkContainer GtkPaned where gtkContainer (GtkPaned p) = GtkContainer p
 
@@ -378,6 +423,8 @@ packPane2 (GtkPaned p) resize shrink widget =
 	toState (gtk_paned_pack2 p w resize=:Resize shrink=:Shrink) >>|
 	pure widget
 
+:: GtkScrolledWindow =: GtkScrolledWindow Pointer
+
 instance gtkWidget GtkScrolledWindow where gtkWidget (GtkScrolledWindow sw) = GtkWidget sw
 instance gtkContainer GtkScrolledWindow where gtkContainer (GtkScrolledWindow sw) = GtkContainer sw
 
@@ -393,6 +440,8 @@ where
 		toState (gtk_scrolled_window_set_policy sw (toInt hp) (toInt vp)) >>|
 		pure window
 
+:: GtkSearchEntry =: GtkSearchEntry Pointer
+
 instance gtkWidget GtkSearchEntry where gtkWidget (GtkSearchEntry se) = GtkWidget se
 instance gtkEntry GtkSearchEntry where gtkEntry (GtkSearchEntry se) = GtkEntry se
 
@@ -401,6 +450,8 @@ newSearchEntry =
 	toStateR gtk_search_entry_new >>= \se ->
 	show (GtkSearchEntry se)
 
+:: GtkSeparator =: GtkSeparator Pointer
+
 instance gtkWidget GtkSeparator where gtkWidget (GtkSeparator s) = GtkWidget s
 
 newSeparator :: !GtkOrientation -> GtkM GtkSeparator
@@ -408,6 +459,8 @@ newSeparator orientation =
 	toStateR (gtk_separator_new orientation=:Vertical) >>= \s ->
 	show (GtkSeparator s)
 
+:: GtkSpinner =: GtkSpinner Pointer
+
 instance gtkWidget GtkSpinner where gtkWidget (GtkSpinner s) = GtkWidget s
 
 newSpinner :: GtkM GtkSpinner
@@ -425,6 +478,8 @@ stopSpinner spinner=:(GtkSpinner s) =
 	toState (gtk_spinner_stop s) >>|
 	pure spinner
 
+:: GtkTextBuffer =: GtkTextBuffer Pointer
+
 instance tune GtkTextBuffer GtkText
 where
 	tune (Text s) buffer=:(GtkTextBuffer b) =
@@ -446,6 +501,8 @@ insertAtCursor s buffer=:(GtkTextBuffer b) =
 	toState (gtk_text_buffer_insert_at_cursor b s (size s)) >>|
 	pure buffer
 
+:: GtkTextView =: GtkTextView Pointer
+
 instance gtkWidget GtkTextView where gtkWidget (GtkTextView tv) = GtkWidget tv
 instance gtkContainer GtkTextView where gtkContainer (GtkTextView tv) = GtkContainer tv
 
@@ -464,6 +521,8 @@ where
 		toState (gtk_text_view_set_wrap_mode tv (toInt mode)) >>|
 		pure view
 
+:: GtkTreeView =: GtkTreeView Pointer
+
 instance gtkWidget GtkTreeView where gtkWidget (GtkTreeView tv) = GtkWidget tv
 
 newTreeView :: !GtkListStore -> GtkM GtkTreeView
@@ -512,8 +571,16 @@ selectPath path (GtkTreeView tv) =
 		(toState (gtk_tree_selection_select_iter selection iter) >>| pure True)
 		(pure False)
 
+:: GtkWidget =: GtkWidget Pointer
+
 instance gtkWidget GtkWidget where gtkWidget w = w
 
+toPtr :: !w -> Pointer | gtkWidget w
+toPtr widget = let (GtkWidget w) = gtkWidget widget in w
+
+unsafeToWidget :: !Pointer -> GtkWidget
+unsafeToWidget w = GtkWidget w
+
 show :: !w -> GtkM w | gtkWidget w
 show widget =
 	let (GtkWidget w) = gtkWidget widget in
@@ -605,6 +672,8 @@ where
 		toState (gtk_widget_set_size_request w width height) >>|
 		pure widget
 
+:: GtkWindow =: GtkWindow Pointer
+
 instance gtkWidget GtkWindow where gtkWidget (GtkWindow w) = GtkWidget w
 instance gtkContainer GtkWindow where gtkContainer (GtkWindow w) = GtkContainer w
 instance gtkWindow GtkWindow where gtkWindow w = w
diff --git a/src/Gtk/Widgets/Sheet.dcl b/src/Gtk/Widgets/Sheet.dcl
index 0f365d2..5a4191d 100644
--- a/src/Gtk/Widgets/Sheet.dcl
+++ b/src/Gtk/Widgets/Sheet.dcl
@@ -22,7 +22,7 @@ from Gtk.Widgets import
 
 import Gtk.Widgets.Sheet.Signal
 
-:: GtkSheet =: GtkSheet Pointer
+:: GtkSheet (=: GtkSheet Pointer)
 
 instance gtkWidget GtkSheet
 instance gtkContainer GtkSheet
diff --git a/src/Gtk/Widgets/Sheet.icl b/src/Gtk/Widgets/Sheet.icl
index 36d0b4d..c28816f 100644
--- a/src/Gtk/Widgets/Sheet.icl
+++ b/src/Gtk/Widgets/Sheet.icl
@@ -11,8 +11,8 @@ import Gtk.Widgets.Sheet.Internal
 
 :: GtkSheet =: GtkSheet Pointer
 
-instance gtkWidget GtkSheet    where gtkWidget (GtkSheet s) = GtkWidget s
-instance gtkContainer GtkSheet where gtkContainer (GtkSheet s) = GtkContainer s
+instance gtkWidget GtkSheet    where gtkWidget (GtkSheet s) = unsafeToWidget s
+instance gtkContainer GtkSheet where gtkContainer (GtkSheet s) = unsafeToContainer s
 
 newSheet :: !Int !Int !String -> GtkM GtkSheet
 newSheet nrows ncols title =
@@ -105,7 +105,7 @@ setActiveCell row col sheet=:(GtkSheet s) =
 getEntry :: !GtkSheet -> GtkM GtkEntry
 getEntry (GtkSheet s) =
 	toStateR (gtk_sheet_get_entry s) >>= \e ->
-	pure (GtkEntry e)
+	pure (unsafeToEntry e)
 
 instance tune GtkSheet GtkSheetColumnResizability
 where