TreeView::setOpenCloseButtonsVisible() How to Make Buttons Visible?

I must be an idiot.
I have used TreeView many times and have always simply said ‘Oh well, I do not have ‘+’ and ‘-’ signs on my TreeViewItems’.

I have annoyed myself enough now that I desire to know what I am doing wrong!
I assume that setOpenCloseButtonsVisible(true) will cause the ‘+’ and ‘-’ signs to appear on my TreeViewItems.

What am I missing?

Thanks in advance.

Just to rule out the obvious, did you check mightContainSubItems():

Tells the tree whether this item can potentially be opened.

If your item could contain sub-items, this should return true; if it returns false then the tree will not try to open the item. This determines whether or not the item will be drawn with a ‘plus’ button next to it.

Thanks Daniel, but that is not it.
After much looking, debugging, stepping thru, … I suddenly realized my background of the component in which the TreeView is imbedded in is black!

LookAndFeel_V3::drawTreeviewPlusMinusBox() is pathing a triangle with color (backgroundColour.contrasting().withAlpha (isMouseOver ? 0.5f : 0.3f) (which is a gray due to me using the default LookAndFeel).

It simply does not show up on a black background.

Since I refuse to change my background from black, and I really do not like the triangle (I prefer +,-) I guess I am off to overriding LookAndFeel_V3::drawTreeviewPlusMinusBox() in a derived LookAndFeel. Darn.

Thanks, Resolved.