Hi Pradeep,
Thank you for your interest in Syncfusion products.
We have made this controls re-arrangement using flowlayout as a feature request # 734. You can keep track of the following link to know the status of this issue.
Feature Request # 734 - Ability to rearrange the controls laid out by flow layout in the designer.We will try our very best to implement this feature at the earliest and keep you informed.
Best Regards,
Bhuvana