by checking has_focus() for m_xHexCodeText and m_xDecimalCodeText.
Also,CharHighlightHdl and SearchCharHighlightHdl now look alike.
Also add case for missing glyph for entered hex/dec code.

Change-Id: I32c782ac09756462f11b209afa12183d5ae7ac1f
Reviewed-on: https://gerrit.libreoffice.org/51616Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>