Problem with scrolling in SubCanvas with MouseWheel

If i make a window with a subcanvas which is set to have a vertical
scrollbar, scrolling with the mousewheel does not work (probably a
horizontal one doesn't work either). It seems to be a problem of the
subcanvas, as scrolling with the mousewheel has no problems in lists and
other windows.

You can check this by creating a new subclass of ApplicationModel.  
Create a windowSpec containing a subcanvas. Create another spec with
arbitrary content and tell the subcanvas to have this second spec as
content. Then tell the subcanvas to have a vertical scrollbar. Install
and open. Scrolling does work, but scrolling with the mousewheel does not.

Is this a known problem and is there a solution to fix this (i checked
VW 7.3.1 and VW 7.4.1)?

Volker