Use RadGridView and RadDropDownList controls to create the user control of the parent form, and then create a sub-form user control named AbutBodyMtdPageBase to inherit the parent form, and create a new UserControl named AbutBodyTpMtdPage, and then drag the sub-form user control of AbutBodyMtdPageBase to enter AbutBodyTpMtdPage, create a new Form form, drag AbutBodyTpMtdPage into the Form, and the RadGridView form does not display data during program execution.
The above descriptions are all created user controls, and finally a new Form is created.
Thank you for the provided image.
Although this gives me a general idea of your scenario, it is hard for me to determine the cause of the issue without replicating it at my end. Would you be able to demonstrate the issue you observe in a small sample project so that I can further investigate?
On a side note, I notice you mention the Form control which is specific to the Windows Forms framework, but you've posted this thread in the WPF forums. Is this intentional?