do you really need this new variable m_collapsedResultCount here? You're clearing m_resultsItems anyway. Why not to check like

if (m_expression->results().size())
{
    if (m_resultItems.size())
        //result(s) available and result item(s) shown -> allow to hide
    else
        //result(s) available but result item(s) hidden  -> allow to show
}

?

won't we run into problems with the performance for rendered image results for example? Do we really need to remove items and create them again? Why not to simple hide/show them without deleting them?

lower case for variables. Maybe use 'promt' as the name of the variable?

expandResults()

I think, we really need this variable in updateEntry. updateEntry called, when we redraw worksheet or when we have new result. So, m_collapsedResultCount, stored count of collapsed results, needed to distinguish the first situation from the second.

I agree, this is not very effective. But, I can't found another solution. I have tried show/hide; disable/enable, but results item in this cases don't free their places, so we have empty space between command entries. So, I open to suggestions