Hi Kovacs,
Sorry for the inconvenience,
We have confirmed that the issue with “The medium size radiobutton checked sign is not center” is a defect and logged a defect report.
Query: I couldn't open API's submenu.
We are unable to understand this query clearly. Please provide more information on your query and which component API’s submenu could not open.
A support incident to track the status of this defect has been created under your account. Please log on to our support website to check for further updates.
https://www.syncfusion.com/account/login?ReturnUrl=%2fsupport%2fdirecttrac%2fincidents
Regards,
Selvamani S