Borrow pluma-close-button class and use it.

This is a subclass of GtkButton special theming for the close button.

taken from:
https://git.gnome.org/browse/gnome-terminal/commit/src?h=gnome-3-8&id=c3a3e06
https://git.gnome.org/browse/gnome-terminal/diff/src/terminal-close-button.c?h=gnome-3-8&id=2bff4b6

src/Makefile.am

@@ -23,6 +23,8 @@ mate_terminal_SOURCES= \
 	terminal-accels.h \
 	terminal-app.c \
 	terminal-app.h \
+	terminal-close-button.h \
+	terminal-close-button.c \
 	terminal-debug.c \
 	terminal-debug.h \
 	terminal-encoding.c \

src/terminal-close-button.c

@@ -0,0 +1,74 @@
+/*
+ * terminal-close-button.c
+ *
+ * Copyright © 2010 - Paolo Borelli
+ * Copyright © 2011 - Ignacio Casal Quinteiro
+ * Copyright © 2016 - Wolfgang Ulbrich
+ *
+ * Mate-terminal is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Mate-terminal is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+
+#include "terminal-close-button.h"
+
+struct _TerminalCloseButtonClassPrivate {
+	GtkCssProvider *css;
+};
+
+G_DEFINE_TYPE_WITH_CODE (TerminalCloseButton, terminal_close_button, GTK_TYPE_BUTTON,
+                         g_type_add_class_private (g_define_type_id, sizeof (TerminalCloseButtonClassPrivate)))
+
+static void
+terminal_close_button_class_init (TerminalCloseButtonClass *klass)
+{
+	static const gchar button_style[] =
+		"* {\n"
+		  "padding: 0;\n"
+		"}";
+
+	klass->priv = G_TYPE_CLASS_GET_PRIVATE (klass, TERMINAL_TYPE_CLOSE_BUTTON, TerminalCloseButtonClassPrivate);
+
+	klass->priv->css = gtk_css_provider_new ();
+	gtk_css_provider_load_from_data (klass->priv->css, button_style, -1, NULL);
+}
+
+static void
+terminal_close_button_init (TerminalCloseButton *button)
+{
+	GtkWidget *image;
+	GtkStyleContext *context;
+
+	gtk_widget_set_name (GTK_WIDGET (button), "mate-terminal-tab-close-button");
+
+	image = gtk_image_new_from_icon_name ("window-close", GTK_ICON_SIZE_MENU);
+	gtk_widget_show (image);
+
+	gtk_container_add (GTK_CONTAINER (button), image);
+
+	context = gtk_widget_get_style_context (GTK_WIDGET (button));
+	gtk_style_context_add_provider (context,
+	                                GTK_STYLE_PROVIDER (TERMINAL_CLOSE_BUTTON_GET_CLASS (button)->priv->css),
+	                                GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+}
+
+GtkWidget *
+terminal_close_button_new ()
+{
+	return GTK_WIDGET (g_object_new (TERMINAL_TYPE_CLOSE_BUTTON,
+	                                 "relief", GTK_RELIEF_NONE,
+	                                 "focus-on-click", FALSE,
+	                                 NULL));
+}
+

src/terminal-close-button.h

@@ -0,0 +1,59 @@
+/*
+ * terminal-close-button.h
+ *
+ * Copyright © 2010 - Paolo Borelli
+ * Copyright © 2016 - Wolfgang Ulbrich
+ *
+ * Mate-terminal is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Mate-terminal is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __TERMINAL_CLOSE_BUTTON_H__
+#define __TERMINAL_CLOSE_BUTTON_H__
+
+#include <gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+#define TERMINAL_TYPE_CLOSE_BUTTON			(terminal_close_button_get_type ())
+#define TERMINAL_CLOSE_BUTTON(obj)			(G_TYPE_CHECK_INSTANCE_CAST ((obj), TERMINAL_TYPE_CLOSE_BUTTON, TerminalCloseButton))
+#define TERMINAL_CLOSE_BUTTON_CONST(obj)		(G_TYPE_CHECK_INSTANCE_CAST ((obj), TERMINAL_TYPE_CLOSE_BUTTON, TerminalCloseButton const))
+#define TERMINAL_CLOSE_BUTTON_CLASS(klass)		(G_TYPE_CHECK_CLASS_CAST ((klass), TERMINAL_TYPE_CLOSE_BUTTON, TerminalCloseButtonClass))
+#define TERMINAL_IS_CLOSE_BUTTON(obj)		(G_TYPE_CHECK_INSTANCE_TYPE ((obj), TERMINAL_TYPE_CLOSE_BUTTON))
+#define TERMINAL_IS_CLOSE_BUTTON_CLASS(klass)	(G_TYPE_CHECK_CLASS_TYPE ((klass), TERMINAL_TYPE_CLOSE_BUTTON))
+#define TERMINAL_CLOSE_BUTTON_GET_CLASS(obj)	(G_TYPE_INSTANCE_GET_CLASS ((obj), TERMINAL_TYPE_CLOSE_BUTTON, TerminalCloseButtonClass))
+
+typedef struct _TerminalCloseButton		TerminalCloseButton;
+typedef struct _TerminalCloseButtonPrivate	TerminalCloseButtonPrivate;
+typedef struct _TerminalCloseButtonClass	TerminalCloseButtonClass;
+typedef struct _TerminalCloseButtonClassPrivate	TerminalCloseButtonClassPrivate;
+
+struct _TerminalCloseButton
+{
+	GtkButton parent;
+};
+
+struct _TerminalCloseButtonClass
+{
+	GtkButtonClass parent_class;
+
+	TerminalCloseButtonClassPrivate *priv;
+};
+
+GType		  terminal_close_button_get_type (void) G_GNUC_CONST;
+
+GtkWidget	 *terminal_close_button_new      (void);
+
+G_END_DECLS
+
+#endif /* __TERMINAL_CLOSE_BUTTON_H__ */

src/terminal-tab-label.c

@@ -23,6 +23,7 @@
 
 #include "terminal-intl.h"
 #include "terminal-tab-label.h"
+#include "terminal-close-button.h"
 
 #define TERMINAL_TAB_LABEL_GET_PRIVATE(tab_label)(G_TYPE_INSTANCE_GET_PRIVATE ((tab_label), TERMINAL_TYPE_TAB_LABEL, TerminalTabLabelPrivate))
 
@@ -91,22 +92,6 @@ terminal_tab_label_parent_set (GtkWidget *widget,
 		parent_set (widget, old_parent);
 }
 
-static void
-terminal_tab_label_style_set (GtkWidget *widget,
-                              GtkStyle *previous_style)
-{
-	TerminalTabLabel *tab_label = TERMINAL_TAB_LABEL (widget);
-	TerminalTabLabelPrivate *priv = tab_label->priv;
-	void (* style_set) (GtkWidget *, GtkStyle *) = GTK_WIDGET_CLASS (terminal_tab_label_parent_class)->style_set;
-	int h, w;
-
-	if (style_set)
-		style_set (widget, previous_style);
-
-	gtk_icon_size_lookup (GTK_ICON_SIZE_MENU, &w, &h);
-	gtk_widget_set_size_request (priv->close_button, w + 2, h + 2);
-}
-
 static void
 terminal_tab_label_init (TerminalTabLabel *tab_label)
 {
@@ -121,7 +106,7 @@ terminal_tab_label_constructor (GType type,
 	GObject *object;
 	TerminalTabLabel *tab_label;
 	TerminalTabLabelPrivate *priv;
-	GtkWidget *hbox, *label, *close_button, *image;
+	GtkWidget *hbox, *label, *close_button;
 
 	object = G_OBJECT_CLASS (terminal_tab_label_parent_class)->constructor
 	         (type, n_construct_properties, construct_params);
@@ -148,15 +133,9 @@ terminal_tab_label_constructor (GType type,
 
 	gtk_box_pack_start (GTK_BOX (hbox), label, TRUE, TRUE, 0);
 
-	priv->close_button = close_button = gtk_button_new ();
+	priv->close_button = close_button = terminal_close_button_new ();
-	gtk_button_set_relief (GTK_BUTTON (close_button), GTK_RELIEF_NONE);
-	gtk_button_set_focus_on_click (GTK_BUTTON (close_button), FALSE);
-	gtk_button_set_relief (GTK_BUTTON (close_button), GTK_RELIEF_NONE);
-	gtk_widget_set_name (close_button, "mate-terminal-tab-close-button");
 	gtk_widget_set_tooltip_text (close_button, _("Close tab"));
 
-	image = gtk_image_new_from_icon_name ("window-close", GTK_ICON_SIZE_MENU);
-	gtk_container_add (GTK_CONTAINER (close_button), image);
 	gtk_box_pack_end (GTK_BOX (hbox), close_button, FALSE, FALSE, 0);
 
 	sync_tab_label (priv->screen, NULL, label);
@@ -210,7 +189,6 @@ terminal_tab_label_class_init (TerminalTabLabelClass *klass)
 	gobject_class->set_property = terminal_tab_label_set_property;
 
 	widget_class->parent_set = terminal_tab_label_parent_set;
-	widget_class->style_set = terminal_tab_label_style_set;
 
 	signals[CLOSE_BUTTON_CLICKED] =
 	    g_signal_new (I_("close-button-clicked"),

src/terminal-window.c

@@ -2131,16 +2131,6 @@ terminal_window_class_init (TerminalWindowClass *klass)
     widget_class->screen_changed = terminal_window_screen_changed;
 
     g_type_class_add_private (object_class, sizeof (TerminalWindowPrivate));
-
-    gtk_rc_parse_string ("style \"mate-terminal-tab-close-button-style\"\n"
-                         "{\n"
-                         "GtkWidget::focus-padding = 0\n"
-                         "GtkWidget::focus-line-width = 0\n"
-                         "xthickness = 0\n"
-                         "ythickness = 0\n"
-                         "}\n"
-                         "widget \"*.mate-terminal-tab-close-button\" style \"mate-terminal-tab-close-button-style\"");
-
 }
 
 static void