fix undo problem

src/views/Stage.ts

@@ -249,6 +249,12 @@ export class Stage extends Laya.Script {
             }
             this.onSetBlock(this.selectedBlock)
             this.onUpdateScore()
+            var undos = this.data.get_undos()
+            if (undos.length > 0) {
+                var last = undos[undos.length-1]
+                this.selectedBlock = this.blocks[last.index]
+                this.onApplyBlock(this.selectedBlock)
+            }
         }
     }