fix: 表字段列排序组件首位排序无效问题

src/components/TableColumnsDnd/index.vue

@@ -62,7 +62,7 @@ function fnTableColumnsCheckAllChange(e: any) {
 /**表格字段列拖拽操作 */
 function fnTableColumnsDrop(dropResult: any) {
   const { removedIndex, addedIndex, payload } = dropResult;
-  if (!removedIndex || !addedIndex) {
+  if (removedIndex === null || addedIndex === null) {
     return;
   }
   let itemToAdd = payload;
@@ -184,6 +184,7 @@ onMounted(() => {
                 <a-button
                   v-if="c.fixed !== undefined"
                   size="small"
+                  :title="c.fixed ? `Fixed ${c.fixed} side` : ''"
                   :type="c.fixed ? 'primary' : 'dashed'"
                   @click="fnTableColumnsFixed(c)"
                 >