Scintilla changes:

Hijack SCI_LOADLEXERLIBRARY for programmatically setting input method.
This is helpful on newer versions of macOS, where changing the input method is
flaky.

diff -r 6e368ee248e4 gtk/ScintillaGTK.cxx
--- a/gtk/ScintillaGTK.cxx	Fri Oct 26 11:06:34 2018 -0400
+++ b/gtk/ScintillaGTK.cxx	Sun Nov 25 00:20:58 2018 -0500
@@ -821,6 +821,11 @@
 		case SCI_GETDIRECTPOINTER:
 			return reinterpret_cast<sptr_t>(this);
 
+		case SCI_LOADLEXERLIBRARY:
+			// Hijack this interface to programmatically set input method.
+			gtk_im_multicontext_set_context_id(GTK_IM_MULTICONTEXT(im_context), ConstCharPtrFromSPtr(lParam));
+			break;
+
 		case SCI_TARGETASUTF8:
 			return TargetAsUTF8(CharPtrFromSPtr(lParam));