Hi @ChongJingHong,
The issue appears to be that the z-index values of the dialog and the dropdown components in use do not work well together. We’d need to know a little more about the specific components you’re using to understand the problem and recommend a solution.
Can you copy the source code you’re using that results in this?
Additionally, it would be helpful if you could open your browser’s devtools, inspect both the modal dialog element and the open dropdown element, and copy the “computed properties” for each element here so we can see the z-index values they receive and where they came from.
Here’s an example screenshot showing the latter:
Cheers,
Daz