Hi Prasant,
Sorry for the inconvenience caused.
I am afraid, I was not able to reproduce this issue. Could you please let me whether you have set the following constraints for the panel (Fill ->Both and equal weights - WeightX and WeightY as 0.5).
Could you please provide more information regarding your problem. Also, please send us a sample which reproduces the issue or modify the sample attached.
GridBag.zip
Thanks for your patience.
Thanks for using Syncfusion products.
Best Regards,
Seetha