Or at the look of the disabled toolbar icons, they look much better on wxWidgets 3.x
. Plus the fact that only wxWidgets 3.x ships with the Tango-Style Art-Provider.
This is indeed the problem, your application uses wxWidgets 3.x and by default this version includes three different Art-Providers: Native, Tango and Standard, wxWidgets 2.8 only has Standard. Sadly you cannot choose directly at runtime which one to use, they form are chain and are tried in order until the ressource is found. You can either recompile your library and disable Tango (with setup.h) or you can go the crazy route and wxArtProvider::Pop() one (or two if wxArtProvider::HasNativeProvider() returns true) at runtime, but the Standard provider returns quite some ugly icons for some items. Or you can figure out how to access the Standard icons directly, because they are included in the library, but this for sure is the least portable way
.