[vte] widget: Set terminal input purpose

[Christian Persch <chpe src gnome org>]

commit 8f5724c2d9d6bb00966a705ac7ea535fe8b4bbb4
Author: Zander Brown <zbrown gnome org>
Date:   Mon Jan 20 21:55:24 2020 +0100

    widget: Set terminal input purpose
    
    This enables OSKs to show keys not usually shown, like Control.
    
    Fixes: https://gitlab.gnome.org/GNOME/vte/issues/212

 src/widget.cc | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/src/widget.cc b/src/widget.cc
index afc429e2..a8bd6c36 100644
--- a/src/widget.cc
+++ b/src/widget.cc
@@ -304,6 +304,11 @@ Widget::realize() noexcept
 
         assert(!m_im_context);
        m_im_context = gtk_im_multicontext_new();
+#if GTK_CHECK_VERSION (3, 24, 14)
+        g_object_set(m_im_context.get(),
+                     "input-purpose", GTK_INPUT_PURPOSE_TERMINAL,
+                     nullptr);
+#endif
        gtk_im_context_set_client_window(m_im_context.get(), m_event_window);
        g_signal_connect(m_im_context.get(), "commit",
                         G_CALLBACK(im_commit_cb), this);