wxWidgets 2.8.5 has issues, so might wish to try 2.8.4 or if you wish to try the pre-released 2.8.6.
I have no idea if dw2 can cause issues, but I think you would need to compile both wxWidgets and your project using dw2 for it to have a chance to work right. If they are not the same issues WILL likely happen.
Tim S
My test results
Good with C::B SVN 3803, wxWidgets 2.8.6, compiled by MinGW 3.4.5 and Project compiled by MinGW 3.4.5
Good with C::B SVN 3803, wxWidgets 2.8.6, compiled by MinGW 3.4.5 and Project compiled by MinGW 4.2.1-sjlj
Good with C::B SVN 3803, wxWidgets 2.8.6, compiled by MinGW 3.4.5 and Project compiled by MinGW 4.2.1-dw2-2
Good with C::B SVN 3803, wxWidgets 2.8.5, compiled by MinGW 3.4.5 and Project compiled by MinGW 4.2.1-dw2-2
I do not see the problem with the default wxWidgets code, so done testing.