docs: Add some cross references

Refer to the new coordinate system overview
from a couple of places where it is useful.

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index c030a43b4da3b3c7969bab198e241ec528db3e17..50fd4fef29b39b951d527283815f26b44b102a66 100644 (file)
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -10279,6 +10279,9 @@ gtk_widget_pick (GtkWidget    *widget,
  * when @widget and @target do not share a common ancestor. In that
  * case @out_transform gets set to the identity matrix.
  *
+ * To learn more about widget coordinate systems, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: %TRUE if the transform could be computed, %FALSE otherwise
  */
 gboolean
@@ -10353,7 +10356,9 @@ gtk_widget_compute_transform (GtkWidget         *widget,
  *
  * Computes the bounds for @widget in the coordinate space of @target.
  *
- * FIXME: Explain what "bounds" are.
+ * The bounds of widget are (the bounding box of) the region that it is
+ * expected to draw in. See the [coordinate system](coordinates.html)
+ * overview to learn more.
  *
  * If the operation is successful, %TRUE is returned. If @widget has no
  * bounds or the bounds cannot be expressed in @target's coordinate space
@@ -10396,6 +10401,9 @@ gtk_widget_compute_bounds (GtkWidget       *widget,
  *
  * Returns the width that has currently been allocated to @widget.
  *
+ * To learn more about widget sizes, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: the width of the @widget
  */
 int
@@ -10416,6 +10424,9 @@ gtk_widget_get_allocated_width (GtkWidget *widget)
  *
  * Returns the height that has currently been allocated to @widget.
  *
+ * To learn more about widget sizes, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: the height of the @widget
  */
 int
@@ -12430,6 +12441,9 @@ gtk_widget_get_can_target (GtkWidget *widget)
  *
  * For pointer events, see [method@Gtk.Widget.contains].
  *
+ * To learn more about widget sizes, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: The width of @widget
  */
 int
@@ -12454,6 +12468,9 @@ gtk_widget_get_width (GtkWidget *widget)
  *
  * For pointer events, see [method@Gtk.Widget.contains].
  *
+ * To learn more about widget sizes, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: The height of @widget
  */
 int
@@ -12481,6 +12498,9 @@ gtk_widget_get_height (GtkWidget *widget)
  * writing orientation-independent code, such as when
  * implementing [iface@Gtk.Orientable] widgets.
  *
+ * To learn more about widget sizes, see the coordinate
+ * system [overview](coordinates.html).
+ *
  * Returns: The size of @widget in @orientation.
  */
 int