RFR: 4984: Label missing for Focus Selection combobox

[Suchita Chaturvedi]

Added a new label for Selection combo box. This was an issue pointed out by vpat.

Please review the change.

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Commit messages:
 - 4984: Label missing for Focus Selection combobox

Changes: https://git.openjdk.java.net/jmc/pull/161/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=161&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-4984
  Stats: 8 lines in 3 files changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jmc/pull/161.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/161/head:pull/161

PR: https://git.openjdk.java.net/jmc/pull/161