SG-15889: SWT, macOS: ignore events for disposed widgets

workaround for https://bugs.eclipse.org/bugs/show_bug.cgi?id=436228

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/Display.java

@@ -6091,15 +6091,19 @@ static long windowProc(long id, long sel) {
 	Widget widget = LookupWidget(id, sel);
 	if (widget == null) return 0;
 
+	if (sel == OS.sel_dealloc) {
+		widget.dealloc(id, sel);
+		return 0;
+	}
+
+	// might happen rarely and causes assertions later, e.g. https://bugs.eclipse.org/bugs/show_bug.cgi?id=436228
+	if (widget.display == null) return 0;
+
 	return switch (Selector.valueOf(sel)) {
 	case sel_sendSelection -> {
 		widget.sendSelection();
 		yield 0;
 	}
-	case sel_dealloc -> {
-		widget.dealloc(id, sel);
-		yield 0;
-	}
 	case sel_sendDoubleSelection -> {
 		widget.sendDoubleSelection();
 		yield 0;
@@ -6243,6 +6247,9 @@ static long windowProc(long id, long sel, long arg0) {
 	Widget widget = LookupWidget(id, sel);
 	if (widget == null) return 0;
 
+	// might happen rarely and causes assertions later, e.g. https://bugs.eclipse.org/bugs/show_bug.cgi?id=436228
+	if (widget.display == null) return 0;
+
 	return switch (Selector.valueOf(sel)) {
 	case sel_windowWillClose_ -> {
 		widget.windowWillClose(id, sel, arg0);