There is something wrong with HTML plug-ins running on the flex-base vSphere Client(version 6.0) on IE(version 11) , the problem shows that the action extension of datacenter cannot display completely and it blocks users' operations.
Thanks for the report.
I could reproduce this problem in the Web Client (Flex). While it has an impact on plugins it is not a problem in the SDK but a product issue with the menu specifically related to IE 11. Please note that while supported IE 11 has a number of limitations and is not recommended.
I will pass it on to be addressed in a future release.