Fix mask delete undo

Sources/arm/ui/TabLayers.hx

@@ -204,10 +204,10 @@ class TabLayers {
 						UIMenu.draw(function(ui: Zui) {
 							ui.text('${l.name} ' + tr("Mask"), Right, ui.t.HIGHLIGHT_COL);
 							if (ui.button(tr("Delete"), Left)) {
-								Context.setLayer(l);
+								Context.setLayer(l, true);
 								History.deleteMask();
 								l.deleteMask();
-								Context.setLayer(l);
+								Context.setLayer(l, false);
 							}
 							if (ui.button(tr("Clear to Black"), Left)) {
 								function clear(g: kha.graphics4.Graphics) {

Sources/arm/ui/UISidebar.hx

@@ -616,7 +616,7 @@ class UISidebar {
 					var source = l.texpaint_mask;
 					var g2 = target.g2;
 					g2.begin(true, 0x00000000);
-					g2.pipeline = Layers.pipeCopy;
+					g2.pipeline = Layers.pipeCopy8;
 					g2.drawScaledImage(source, 0, 0, target.width, target.height);
 					g2.pipeline = null;
 					g2.end();