I'm trying to implement hide function in my application.
What I want is to have this little arrow ">" when is hide and "V" when is visible.
I know how to make it so its hides and shows but I need that little arrow to change whenever I click on it....

I'm using quickly and python to create my app.
I tried set_icon_from_stock function but it returns error:

AttributeError: 'ToolButton' object has no attribute 'set_icon_from_stock'

Above example of arrow I talking about.

Thanks