Comment 7 for bug 893174

git clone git://git.gnome.org/vte
git show 31b4047a | grep -B6 -A3 '^\+.*inner-border'
+#if GTK_CHECK_VERSION (2, 99, 0)
+ klass->priv = G_TYPE_CLASS_GET_PRIVATE (klass, VTE_TYPE_TERMINAL, VteTerminalClassPrivate);
+
+ klass->priv->style_provider = GTK_STYLE_PROVIDER (gtk_css_provider_new ());
+ gtk_css_provider_load_from_data (GTK_CSS_PROVIDER (klass->priv->style_provider),
+ "VteTerminal {\n"
+ "-VteTerminal-inner-border: 1;\n"
+ "}\n",
+ -1, NULL);
+#endif /* GTK 3.0 */

commit 31b4047a51ac48264b735a8be24fdddd3b086acc
Author: Christian Persch <email address hidden>
Date: Wed Feb 2 18:45:41 2011 +0100

    Add default style provider

    This fixes the default value for the 'inner-border' property not
    to be NULL.

    Bug #640460.

"shrinking terminal on tab switch"
https://bugzilla.gnome.org/show_bug.cgi?id=640460