Add IM and full wxEVT_CHAR support to wxTextCtrl and wxComboBox in wxGTK.

Generate wxEVT_CHAR events for non-ASCII characters entered in these controls
by intercepting their insert-text signal.

Also try to use GtkEntry/GtkTextView internal IM objects but unsuccessfully so
far.

Closes #3158.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73695 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/combobox.cpp

@@ -173,6 +173,7 @@ bool wxComboBox::Create( wxWindow *parent, wxWindowID id, const wxString& value,
         g_signal_connect_after (entry, "changed",
                                 G_CALLBACK (gtkcombobox_text_changed_callback), this);
 
+        GTKConnectInsertTextSignal(entry);
         GTKConnectClipboardSignals(GTK_WIDGET(entry));
     }