More protection for SvTreeListBox.
More protection for SvTreeListBox.

Change-Id: I55731cd69aa12f5709e300759f556e29e8ceff5d

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core