fdo#73606: Avoid calling MarkDataChanged() when nothing is selected.
fdo#73606: Avoid calling MarkDataChanged() when nothing is selected.

MarkDataChanged() is quite expensive & in theory unnecessary when no
selection is present.

Change-Id: I6967b914735462403a77568010532b37a1d8f333

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