RFR: 8353685: Open some JComboBox bugs 4

[Sergey Bylokhov]

On Fri, 18 Apr 2025 02:30:34 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> Updating and opening some JComboBox bugs
>
> test/jdk/javax/swing/JComboBox/bug4459267.java line 58:
> 
>> 56:             robot.delay(250);
>> 57:         } finally {
>> 58:             if (frame != null) {
> 
> the frame is initialized in another thread.

similar issue exists in other tests

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24733#discussion_r2049921232