Scintilla changes:

* Add Message::ChangeInsertion for programmatically setting input method.
  This is helpful on newer versions of macOS, where changing the input method is flaky.
* Handle leading whitespace in XPM images in order to prevent crashes.
* Add Message::ReplaceRectangular from upstream, which will be in the next release.

diff -r 52d56f79dc0f gtk/ScintillaGTK.cxx
--- a/gtk/ScintillaGTK.cxx	Fri Apr 09 15:11:26 2021 +1000
+++ b/gtk/ScintillaGTK.cxx	Tue Apr 13 16:36:00 2021 -0400
@@ -885,6 +887,11 @@
 		case Message::GetDirectPointer:
 			return reinterpret_cast<sptr_t>(this);
 
+		case Message::ChangeInsertion:
+			// Hijack this interface to programmatically set input method.
+			gtk_im_multicontext_set_context_id(GTK_IM_MULTICONTEXT(im_context), ConstCharPtrFromSPtr(lParam));
+			break;
+
 		case Message::TargetAsUTF8:
 			return TargetAsUTF8(CharPtrFromSPtr(lParam));
 
diff -r 22b6bbb36280 src/XPM.cxx
--- a/src/XPM.cxx	Sat Sep 05 07:55:08 2020 +1000
+++ b/src/XPM.cxx	Fri Oct 02 20:32:13 2020 -0400
@@ -92,6 +92,9 @@
 void XPM::Init(const char *textForm) {
 	// Test done is two parts to avoid possibility of overstepping the memory
 	// if memcmp implemented strangely. Must be 4 bytes at least at destination.
+	while (*textForm == ' ') {
+		textForm++;
+	}
 	if ((0 == memcmp(textForm, "/* X", 4)) && (0 == memcmp(textForm, "/* XPM */", 9))) {
 		// Build the lines form out of the text form
 		std::vector<const char *> linesForm = LinesFormFromTextForm(textForm);
diff -r df18eadcec4b include/Scintilla.h
--- a/include/Scintilla.h	Mon May 31 11:18:20 2021 +1000
+++ b/include/Scintilla.h	Thu Jun 10 15:51:56 2021 -0400
@@ -885,6 +885,7 @@
 #define SCI_TOGGLECARETSTICKY 2459
 #define SCI_SETPASTECONVERTENDINGS 2467
 #define SCI_GETPASTECONVERTENDINGS 2468
+#define SCI_REPLACERECTANGULAR 2771
 #define SCI_SELECTIONDUPLICATE 2469
 #define SCI_SETCARETLINEBACKALPHA 2470
 #define SCI_GETCARETLINEBACKALPHA 2471
diff -r df18eadcec4b include/Scintilla.iface
--- a/include/Scintilla.iface	Mon May 31 11:18:20 2021 +1000
+++ b/include/Scintilla.iface	Thu Jun 10 15:51:56 2021 -0400
@@ -2439,6 +2439,9 @@
 # Get convert-on-paste setting
 get bool GetPasteConvertEndings=2468(,)
 
+# Replace the selection with text like a rectangular paste.
+fun void ReplaceRectangular=2771(position length, string text)
+
 # Duplicate the selection. If selection empty duplicate the line containing the caret.
 fun void SelectionDuplicate=2469(,)
 
diff -r df18eadcec4b include/ScintillaMessages.h
--- a/include/ScintillaMessages.h	Mon May 31 11:18:20 2021 +1000
+++ b/include/ScintillaMessages.h	Thu Jun 10 15:51:56 2021 -0400
@@ -581,6 +581,7 @@
 	ToggleCaretSticky = 2459,
 	SetPasteConvertEndings = 2467,
 	GetPasteConvertEndings = 2468,
+	ReplaceRectangular = 2771,
 	SelectionDuplicate = 2469,
 	SetCaretLineBackAlpha = 2470,
 	GetCaretLineBackAlpha = 2471,
diff -r df18eadcec4b src/Editor.cxx
--- a/src/Editor.cxx	Mon May 31 11:18:20 2021 +1000
+++ b/src/Editor.cxx	Thu Jun 10 15:51:56 2021 -0400
@@ -5940,6 +5940,15 @@
 		EnsureCaretVisible();
 		break;
 
+	case Message::ReplaceRectangular: {
+		UndoGroup ug(pdoc);
+		if (!sel.Empty()) {
+			ClearSelection(); // want to replace rectangular selection contents
+		}
+		InsertPasteShape(CharPtrFromSPtr(lParam), static_cast<Sci::Position>(wParam), PasteShape::rectangular);
+		break;
+	}
+
 	case Message::Clear:
 		Clear();
 		SetLastXChosen();