The most recent version of DialogBlocks, 4.25, is more feature rich than ever! 
There is the relatively recent Analysis Tool which gives "expert" wxWidgets advice on your application and warnings on possible construct problems, and checks for Id name/value conflicts.
Additionally, DialogBlocks addresses wxAUI, providing proper constructs. Validators, variables, and data transfer are also handled, as well as a simplified application help interface.
Of course, the old standby's are still there. Complete and accurate building of wxWidgets libraries on any platform, now with a CFG Configurations Property that allows sorting various builds of wxWidgets on the same platform, by compiler version, dynamic vs static, or any criteria you care to specify.
DialogBlocks generates any build files, makefiles or project files (including project files for Visual Studio 6, 7/7.1, 8 [2005 Express and 2005 paid versions], 9 [2008 Express]), for the supported compilers, which are effectively all compilers capable of using and building wxWidgets.
DialogBlocks generates either full C++ code, or C++ code that operates with XRC.
DialogBlocks is still the only IDE or RAD wxWidgets tool that has responsive, fast support. And this applies to questions, enhancement requests, or bugs. Response is within 2 business days, though I mostly see responses on the order of hours and I've yet to figure out what is classified as a "business day" since responses are just as likely on weekends as weekdays. There is no standing on formality, the inquiry is answered whether from a registered user or from someone just evaluating. Avenue of contact is equally open, either directly to Anthemion or through the anthemion-devtools user group.
While Julian refers to DialogBlocks as having "IDE-like" facilities, I have no problem with just calling it the best wxWidgets IDE I've found!
Take a look if you haven't recently. The DialogBlocks website has also undergone a facelift and is more streamlined while also having more helpful content!
http://www.anthemion.co.uk/dialogblocks/
fyi:
thx,
Dave S.