fix: column splitter appearance

lib/ui/grid/grid.js

@@ -1302,7 +1302,7 @@ export class Grid {
                     });
                 }
                 if (typeof this.onSelectedRowChanged === 'function') {
-                    this.onSelectedRowChanged(selectedIndex);
+                    this.onSelectedRowChanged(-1);
                 }
                 this._var.selectedColumnIndex = -1;
                 return;