fix expand bug when column fixed

Author: huangshuwei

packages/style/ve-table.less

@@ -319,6 +319,15 @@
             }
           }
         }
+
+        // expand row
+        .ve-table-expand-tr {
+          .ve-table-fixed-left {
+            position: sticky;
+            z-index: @ve-fixed-body-cell-index;
+            left: 10px;
+          }
+        }
       }
 
       //  tfooter

packages/ve-table/src/body/expand-tr.jsx

@@ -75,6 +75,33 @@ export default {
                 result[clsName("expand-tr-show")] = true;
             }
 
+            return result;
+        },
+
+        // is last left fixed column
+        lastLeftFixedColumn() {
+            let result = null;
+
+            const fixedLeftColumns = this.colgroups.filter(
+                x => x.fixed === "left"
+            );
+
+            if (fixedLeftColumns.length > 0) {
+                result = fixedLeftColumns[fixedLeftColumns.length - 1].field;
+            }
+
+            return result;
+        },
+
+        // expand td class
+        expandTdClass() {
+            let result = {
+                [clsName("expand-td")]: true
+            };
+
+            if (this.lastLeftFixedColumn) {
+                result[clsName("fixed-left")] = true;
+            }
             return result;
         }
     },
@@ -96,13 +123,18 @@ export default {
         }
     },
     render(h) {
-        const { columnCount, getExpandRowContent, expanRowStyle } = this;
+        const {
+            columnCount,
+            getExpandRowContent,
+            expanRowStyle,
+            expandTdClass
+        } = this;
 
         let content = getExpandRowContent(h);
 
         let result = (
             <tr class={this.expanRowClass}>
-                <td class={clsName("expand-td")} colSpan={columnCount}>
+                <td class={expandTdClass} colSpan={columnCount}>
                     {content}
                 </td>
             </tr>