The fix for JDK-8206246 to enable GTK3 for FX 8u has caused a fatal build failure on our production Oracle Linux 6 build machines. There are two problems that occurred:

1. OL 6 machine does not have the gtk3 packages (we need gtk3-devel). It looks like the gtk3 packages are not available for OL 6.

2. Our OL 6 machines have an older version of GTK2 so we get compilation errors (see below for three such errors).

Until we are able to upgrade to Oracle Linux 7 we will need to backout this change.

Here are three of the errors we see (they are repeated multiple times).

In file included from modules/graphics/src/main/native-glass/gtk/glass_general.h:36:0,
                 from modules/graphics/src/main/native-glass/gtk/glass_general.cpp:25:
modules/graphics/src/main/native-glass/gtk/wrapped.h:33:1: error: 'GSettingsSchemaSource' does not name a type
 GSettingsSchemaSource * wrapped_g_settings_schema_source_get_default (void);
 ^~~~~~~~~~~~~~~~~~~~~

modules/graphics/src/main/native-glass/gtk/glass_general.cpp: In function 'gint glass_gdk_visual_get_depth(GdkVisual*)':
modules/graphics/src/main/native-glass/gtk/glass_general.cpp:507:12: error: 'gdk_visual_get_depth' was not declared in this scope
     return gdk_visual_get_depth(visual);
            ^~~~~~~~~~~~~~~~~~~~

In file included from modules/graphics/src/main/native-glass/gtk/glass_key.cpp:30:0:
modules/graphics/src/main/native-glass/gtk/glass_key.cpp: In function 'void initialize_key()':
modules/graphics/src/main/native-glass/gtk/glass_general.h:54:38: error: 'GDK_KEY_Return' was not declared in this scope
 #define GLASS_GDK_KEY_CONSTANT(key) (GDK_KEY_ ## key)
                                      ^
modules/graphics/src/main/native-glass/gtk/glass_key.cpp:44:43: note: in expansion of macro 'GLASS_GDK_KEY_CONSTANT'