Hello Ning,
This is the expected behavior of the Kendo UI Grid, as paging is always performed before grouping to avoid unnecessary grouping of the whole
dataSource. The desired behavior is not supported, but can be achieved with some custom logic.
As there are no special events, associated with the expanding and collapsing, the developer needs to handle the
click events of the collapse/expand icons (they have classes
.k-icon.k-i-collapse and
.k-icon.k-i-expand respectively), and change the
dataSource.pageSize with the desired value.
Also the groups in view have to be expanded/collapsed programmatically if needed, as demonstrated in the following how-to article:
http://docs.telerik.com/kendo-ui/controls/data-management/grid/how-to/persist-grouped-grid-collapsed-details-state
Let us know if you have other questions about Kendo UI.
Regards,
Dimiter Topalov
Telerik