Have you considered Tk? Visually, it's quite like Win32, but it's fully cross-platform and (as of Tcl 9.0) has basic screen-reader support – so no mucking around with OLEACC shims or IAccessible2, as you'd need for COMCTL32. And it supports virtually everything Win32 does, with the ability to drop down to platform-specific sorcery (i.e., Win32) if the need arises.