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.
* Fix preprocessor condition to enable threading on Linux. This has been committed upstream.
* Fix crash due to re-entrant painting. This has been committed upstream.
* Fixed pixmap leak. This has been committed upstream.

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.get()), 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 b0e5467561f7 -r c44165c2283e gtk/PlatGTK.cxx
--- a/gtk/PlatGTK.cxx	Thu Feb 10 13:57:56 2022 +1100
+++ b/gtk/PlatGTK.cxx	Wed Feb 16 09:13:39 2022 +1100
@@ -214,7 +214,7 @@
 	Supports::FractionalStrokeWidth,
 	Supports::TranslucentStroke,
 	Supports::PixelModification,
-#if !defined(PLAT_GTK_WIN32) && !defined(PLAT_GTK_MACOSX)
+#if defined(G_OS_UNIX) && !defined(__APPLE__)
 	// Pango is not thread-safe on Win32 or macOS
 	Supports::ThreadSafeMeasureWidths,
 #endif
diff -r c44165c2283e -r 58bb44ceae61 gtk/ScintillaGTK.cxx
--- a/gtk/ScintillaGTK.cxx	Wed Feb 16 09:13:39 2022 +1100
+++ b/gtk/ScintillaGTK.cxx	Wed Feb 16 09:32:20 2022 +1100
@@ -2656,13 +2656,13 @@
 
 		rcPaint = GetClientRectangle();
 
-		PLATFORM_ASSERT(rgnUpdate == nullptr);
+		cairo_rectangle_list_t *oldRgnUpdate = rgnUpdate;
 		rgnUpdate = cairo_copy_clip_rectangle_list(cr);
 		if (rgnUpdate && rgnUpdate->status != CAIRO_STATUS_SUCCESS) {
 			// If not successful then ignore
 			fprintf(stderr, "DrawTextThis failed to copy update region %d [%d]\n", rgnUpdate->status, rgnUpdate->num_rectangles);
 			cairo_rectangle_list_destroy(rgnUpdate);
-			rgnUpdate = 0;
+			rgnUpdate = nullptr;
 		}
 
 		double x1, y1, x2, y2;
@@ -2687,7 +2687,7 @@
 		if (rgnUpdate) {
 			cairo_rectangle_list_destroy(rgnUpdate);
 		}
-		rgnUpdate = 0;
+		rgnUpdate = oldRgnUpdate;
 		paintState = PaintState::notPainting;
 	} catch (...) {
 		errorStatus = Status::Failure;
@@ -2759,7 +2759,7 @@
 				  ose->area.x + ose->area.width,
 				  ose->area.y + ose->area.height);
 
-		PLATFORM_ASSERT(rgnUpdate == nullptr);
+		GdkRegion *oldRgnUpdate = rgnUpdate;
 		rgnUpdate = gdk_region_copy(ose->region);
 		const PRectangle rcClient = GetClientRectangle();
 		paintingAllText = rcPaint.Contains(rcClient);
@@ -2779,7 +2779,7 @@
 		if (rgnUpdate) {
 			gdk_region_destroy(rgnUpdate);
 		}
-		rgnUpdate = nullptr;
+		rgnUpdate = oldRgnUpdate;
 	} catch (...) {
 		errorStatus = Status::Failure;
 	}
diff -r 81216c20a4d4 -r 8b16ebf10a3e gtk/PlatGTK.cxx
--- a/gtk/PlatGTK.cxx	Thu Feb 17 21:56:04 2022 +1100
+++ b/gtk/PlatGTK.cxx	Mon Feb 21 09:45:09 2022 +1100
@@ -125,7 +125,7 @@
 	EncodingType et= EncodingType::singleByte;
 	WindowID widSave = nullptr;
 	cairo_t *context = nullptr;
-	UniqueCairo pixmapContext;
+	UniqueCairo cairoOwned;
 	UniqueCairoSurface surf;
 	bool inited = false;
 	UniquePangoContext pcontext;
@@ -303,8 +303,8 @@
 		surf.reset(cairo_surface_create_similar(
 			psurfContext,
 			CAIRO_CONTENT_COLOR_ALPHA, width, height));
-		pixmapContext.reset(cairo_create(surf.get()));
-		context = pixmapContext.get();
+		cairoOwned.reset(cairo_create(surf.get()));
+		context = cairoOwned.get();
 		pcontext.reset(gtk_widget_create_pango_context(PWidget(wid)));
 		PLATFORM_ASSERT(pcontext);
 		SetFractionalPositions(pcontext.get());
@@ -322,7 +322,7 @@
 
 void SurfaceImpl::Release() noexcept {
 	et = EncodingType::singleByte;
-	pixmapContext.reset();
+	cairoOwned.reset();
 	context = nullptr;
 	surf.reset();
 	layout.reset();
@@ -397,7 +397,8 @@
 	PLATFORM_ASSERT(sid);
 	Release();
 	PLATFORM_ASSERT(wid);
-	context = cairo_reference(static_cast<cairo_t *>(sid));
+	cairoOwned.reset(cairo_reference(static_cast<cairo_t *>(sid)));
+	context = cairoOwned.get();
 	pcontext.reset(gtk_widget_create_pango_context(PWidget(wid)));
 	SetFractionalPositions(pcontext.get());
 	// update the Pango context in case sid isn't the widget's surface