libgimpwidgets: add GimpSpinButton

GimpSpinButton is a drop-in replacement for (and a subclass of)
GtkSpinButton.  Unlike GtkSpinButton, it avoids updating the
adjustment value when losing focus, unless the entry text has
changed.  This prevents accidental loss of precision, when the
adjustment value can't be accurately displayed in the entry.

devel-docs/libgimpwidgets/libgimpwidgets-docs.sgml

@@ -136,6 +136,10 @@
     <title>Index of new symbols in GIMP 2.10.4</title>
     <xi:include href="xml/api-index-2.10.4.xml"><xi:fallback /></xi:include>
   </index>
+  <index role="2.10.10" id="api-index-2-10-10">
+    <title>Index of new symbols in GIMP 2.10.10</title>
+    <xi:include href="xml/api-index-2.10.10.xml"><xi:fallback /></xi:include>
+  </index>
   <index role="deprecated" id="api-index-deprecated">
     <title>Index of deprecated symbols</title>
     <xi:include href="xml/api-index-deprecated.xml"><xi:fallback /></xi:include>

devel-docs/libgimpwidgets/libgimpwidgets-sections.txt

@@ -530,6 +530,23 @@ GIMP_TYPE_INT_COMBO_BOX_LAYOUT
 gimp_int_combo_box_layout_get_type
 </SECTION>
 
+<SECTION>
+<FILE>gimpspinbutton</FILE>
+<TITLE>GimpSpinButton</TITLE>
+GimpSpinButton
+gimp_spin_button_new
+gimp_spin_button_new_with_range
+<SUBSECTION Standard>
+GIMP_SPIN_BUTTON
+GIMP_IS_SPIN_BUTTON
+GIMP_TYPE_SPIN_BUTTON
+gimp_spin_button_get_type
+GimpSpinButtonClass
+GIMP_SPIN_BUTTON_CLASS
+GIMP_IS_SPIN_BUTTON_CLASS
+GIMP_SPIN_BUTTON_GET_CLASS
+</SECTION>
+
 <SECTION>
 <FILE>gimpstringcombobox</FILE>
 <TITLE>GimpStringComboBox</TITLE>

devel-docs/libgimpwidgets/libgimpwidgets.types

@@ -46,6 +46,7 @@ gimp_preview_get_type
 gimp_ruler_get_type
 gimp_scrolled_preview_get_type
 gimp_size_entry_get_type
+gimp_spin_button_get_type
 gimp_string_combo_box_get_type
 gimp_unit_combo_box_get_type
 gimp_unit_menu_get_type