It looks like cmake\modules\wxwidgets.cmake contains command
find_package(wxWidgets COMPONENTS core base QUIET)
which results in wrong link order (al least for ld/MinGW/MSWin), That's because the given order of the wxWidgets libraries (i.e. core base) goes directly to the internals of cmake\modules\FindwxWidgets.cmake, where it is converted to linker's option string (showing archives), which is, in turn, fed to ld from command string, that results in unresolved symbols (from wx core lib).
By the way, the comments in FindwxWidgets.cmake suggest different order (i.e. base core) which results in correct build (see attachment).
Built PLplot with command:
cmake -G "MinGW Makefiles" -DwxWidgets_ROOT_DIR=c:/wxWidgets -DwxWidgets_LIB_DIR=c:/wxWidgets/lib/gcc_lib -DCMAKE_INSTALL_PREFIX=c:/PLplot -DCMAKE_VERBOSE_MAKEFILE=ON -DCMAKE_COLOR_MAKEFILE=OFF ..
- MinGW (get-inst-20110802);
- cmake 2.8.6;
- wxWidgets 2.9.2, built in directory c:\wxWidgets (for cmake's WIN32_FIND_STYLE) with command: cd build/msw & mingw32-make.exe -f makefile.gcc BUILD=release MONOLITHIC=0 UNICODE=1 SHARED=0