gplugin/gplugin

Fix some issues with the gtk3 and gtk4 includes when not used in a subproject

Testing Done:
Ran the unit tests and gplugin-gtk4-viewer and verified no issues.

Bugs closed: GPLUGIN-145

Reviewed at https://reviews.imfreedom.org/r/1469/
/*
* Copyright (C) 2011-2020 Gary Kramlich <grim@reaperworld.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <https://www.gnu.org/licenses/>.
*/
#ifndef GPLUGIN_GTK_VIEWER_WINDOW_H
#define GPLUGIN_GTK_VIEWER_WINDOW_H
#include <glib.h>
#include <glib-object.h>
#include <gtk/gtk.h>
#define GPLUGIN_GTK_VIEWER_TYPE_WINDOW (gplugin_gtk_viewer_window_get_type())
G_DECLARE_FINAL_TYPE(
GPluginGtkViewerWindow,
gplugin_gtk_viewer_window,
GPLUGIN_GTK_VIEWER,
WINDOW,
GtkWindow)
G_BEGIN_DECLS
GtkWidget *gplugin_gtk_viewer_window_new(void);
G_END_DECLS
#endif /* GPLUGIN_GTK_VIEWER_WINDOW_H */