Hi Srinivasan,
we appreciate your interest in Syncfusion products.
I can able to see the mentioned issue of the tree view in Popup Container. This type of issue had found in our previous versions of 7.x. In which the tree control disappears as if it tries to show the tool tip that displays the hidden text. This mentioned issue has been fixed in the later versions after 7.3, and if you are using the older versions, you can better upgrade to the latest version which has several fixes including this behavior.
The details regarding the latest version of Essential Studio is specified in the forum and the link is as follows:
http://www.syncfusion.com/support/forums/general/93921/essential-studio-2010-volume-2-final-release-v82018-available-for-downloadLet me know if you have any other concern.
Regards,
Christopher K.