Application Express APEX 5.1.0.00.45 Theme Roller Container Border Radius issue
I have set the radius which works except at the top left and right of the area where the corners are rounded, there seems to be another object behind where the corners don't round. See attached image.
The test I did was to create a new page, add a list region, bring up the theme roller and adjust the container border radius.
I didn't have this issue with Apex 5.0.3.00.03