> is there a possibility to make the toolbar vertical?
I think so. In wxWidgets there is a constant wxTB_VERTICAL.
I can't find it in wxHaskell, but if you would know what number it
stands for you might be able to write
[ style :~ \s -> s .+. n ] (where n is the number)
Ah, Google to the rescue!
wxTB_VERTICAL = 8
According to http://wxappbar.sourceforge.net/pydoc/wxoo.windowdrag.html
tbar <- toolBar f [ style :~ \s -> s .+. 8 ]
This code is untested by the way; I hope it works.