Make margin reactive.

Author: yfwz100

src/components/GridItem.vue

@@ -377,7 +377,15 @@
             },
             maxW: function () {
                 this.tryMakeResizable();
-            }
+            },
+            "$parent.margin": function (margin) {
+                if (!margin || (margin[0] == this.margin[0] && margin[1] == this.margin[1])) {
+                    return;
+                }
+                this.margin = margin.map(m => parseInt(m));
+                this.createStyle();
+                this.emitContainerResized();
+            },
         },
         computed: {
             classObj() {