widgets, themes: Define style for GimpPivotSelector

This patch adds a CSS class name to
GimpPivotSelector so we can define its
CSS style in the GUI.
It also defines the margin-right CSS property
to prevent it be affected by the general
GimpOverlayDialog style.

app/widgets/gimppivotselector.c

@@ -172,6 +172,8 @@ gimp_pivot_selector_class_init (GimpPivotSelectorClass *klass)
                                                         0.0,
                                                         GIMP_PARAM_READWRITE |
                                                         G_PARAM_CONSTRUCT));
+
+  gtk_widget_class_set_css_name (GTK_WIDGET_CLASS (klass), "GimpPivotSelector");
 }
 
 static void

themes/Default/common.css

@@ -410,6 +410,11 @@ scrolledwindow viewport grid, scrolledwindow viewport box {
   background-color: @extreme-bg-color;
 }
 
+/* 9 button toggles on some transformation tools */
+GimpPivotSelector .toggle {
+  margin-right: 0px;
+}
+
 /* Define background on items in Preferences header */
 GimpPrefsBox widget box label,
 GimpPrefsBox widget box image {