Test fails in linux in mach5 nightly testing

-----------System.out:(6/158)----------
Testing Synth l&f
focusGained
popupMenuWillBecomeVisible
Testing l&f : javax.swing.plaf.metal.MetalLookAndFeel
focusGained
waiting popupMenuWillBecomeVisible
----------System.err:(14/930)----------
java.lang.RuntimeException: Context Popup is not coming on Shift + F10 In Synth
at bug4975355.test(bug4975355.java:140)
at bug4975355.main(bug4975355.java:73)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:831)

==================
----------System.out:(12/353)----------
Testing Synth l&f
focusGained
popupMenuWillBecomeVisible
Testing l&f : javax.swing.plaf.metal.MetalLookAndFeel
focusGained
popupMenuWillBecomeVisible
Testing l&f : javax.swing.plaf.nimbus.NimbusLookAndFeel
focusGained
popupMenuWillBecomeVisible
Testing l&f : com.sun.java.swing.plaf.motif.MotifLookAndFeel
focusGained
waiting popupMenuWillBecomeVisible
----------System.err:(14/930)----------
java.lang.RuntimeException: Context Popup is not coming on Shift + F10 In Synth
at bug4975355.test(bug4975355.java:140)
at bug4975355.main(bug4975355.java:73)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:831)