the lens adaptor shadow thing is a known problem even for the G2, and G2 users get around it by either zooming in all the way, or using an external flash. It's kinda demanding to ask for no shadowing, at the same time wanting a good flash and compact body. If the cam is designed to fit a lens adaptor without flash shadow, the internal flash would have to be much higher, thus compromising the size of the body.
Rather than complaining to Canon (which prob can't generate much useful feedback for you guys), maybe you would like to try the following:
1) When you want to use flash, take out the lens adaptor. Since for most flash shots, you won't really need filters like UV or starburst.
2) When taking macros, don't use flash, either use artificial lighting if not enough light, or use long exposure (with tripod).
3) Get an external slave flash, which can be triggered off by your A40's internal flash.
That's all I can help....flash shadowing is indeed an irritant but it occurs for almost all compact cams with protruding adaptor. My c700uz has flash shadowing too at the widest end (38mm), but zooming in a little will get rid of it.