Remove expand/collapse box for user

I have a property grid where the visibility, (ie SetHidden(TRUE/FALSE) ),  of child items is to be offered according to ticking a boolean parent.  The basic functionality of this is no problem.

However, the grid is large and complex so I would like to remove the ability to expand the branch by clicking on the parent's expand/collapse box.  In this way I can limit the amount of info on display at any one time to a managable proportion by preventing the user from opening branches which are not currently active.

Is it possible to remove this box and leave just the item, with its checkbox, and its childs, Hidden or not according to the checkbox?

(I should add that I am very new to Property Grids, so this may very well be a no-brainer.  If so apologies in advance.)