Could you attach your project file (*.cbp)?
Here it is, minus the corrections you suggested earlier.
<?xml version="1.0"?>
<!DOCTYPE CodeBlocks_project_file>
<CodeBlocks_project_file>
<FileVersion major="1" minor="1"/>
<Project>
<Option title="wxWidgets application"/>
<Option makefile="Makefile"/>
<Option makefile_is_custom="0"/>
<Option compiler="0"/>
<Build>
<Target title="default">
<Option output="C:\test\wxWidgets.exe"/>
<Option working_dir="."/>
<Option object_output=".objs"/>
<Option deps_output=".deps"/>
<Option type="0"/>
<Option compiler="0"/>
<Option projectResourceIncludeDirsRelation="0"/>
</Target>
<Environment>
<Variable name="WX_DIR" value="C:\wxWidgets"/>
<Variable name="WX_CFG" value=""/>
</Environment>
</Build>
<Compiler>
<Add option="-pipe"/>
<Add option="-mthreads"/>
<Add option="-Winvalid-pch"/>
<Add option="-include "wx_pch.h""/>
<Add option="-D__GNUWIN32__"/>
<Add option="-D__WXMSW__"/>
<Add option="-DWXUSINGDLL"/>
<Add option="-DUSE_PCH"/>
<Add directory="$(WX_DIR)\include"/>
<Add directory="$(WX_DIR)\lib\gcc_dll$(WX_CFG)\msw"/>
<Add directory="$(WX_DIR)\contrib\include"/>
</Compiler>
<ResourceCompiler>
<Add directory="$(WX_DIR)\include"/>
</ResourceCompiler>
<Linker>
<Add library="wxmsw26"/>
<Add directory="$(WX_DIR)\lib\gcc_dll$(WX_CFG)"/>
</Linker>
<Unit filename="wx_pch.h">
<Option compilerVar="CPP"/>
<Option link="0"/>
<Option weight="0"/>
<Option target="default"/>
</Unit>
</Project>
</CodeBlocks_project_file>